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The directional spectral emissivity of a Ti–48Al–2Nb–2Cr alloy (in at.%), 4822 alloy, and a Ti-43.5Al–4Nb–1Mo-0.1B alloy (in at.%),TNM alloy, used in the aeronautical industry, are measured between 150 and 850 °C. The differences in the emissivity values between both alloys at the lowest temperatures, indicates that the βo phase, only present in TNM, exhibit higher emissivity values. By numerical integration of the measured data, the total directional and hemispherical emissivity have been calculated. At 850 °C the total hemispherical emissivity in vacuum are nearly identical with 0.274 ± 0.006 for the 4822 alloy and 0.273 ± 0.007 for the TNM alloy. The lower emissivity change with temperature measured in TNM alloys is related with the deconvolution of βo phase by diffusion processes. Afterwards, near-normal spectral emissivity measurements are performed in both alloys during isothermal oxidation treatments at 750 °C and 850 °C for 120 h. The emissivity data reveal that the TNM alloy exhibits higher oxidation resistance especially at 750 °C. In parallel, microstructural characterization has been performed before the measurements, after the directional emissivity measurements prior to oxidation and after isothermal oxidations. The formed oxide scale is composed of four layers that coincide with those reported in the literature: an outer layer of TiO2 contiguous with a layer of Al2O3, followed by a TiO2/Al2O3 mixed layer and finally a thin layer of Nb-rich nitride. This mixed layer governs the interferential part of the alloys’ emissivity spectra, which, in combination with the background, determines the overall radiative behavior of the alloys under service conditions.

The influence of sulphur atmosphere on conventionally cast (CM) and on electron beam melted (EBM) γ - TiAl RNT650 alloy exposed to a 1% (vol.) H2S – air atmosphere at 650 °C for 500 h was investigated. The material produced by CM showed a lower mass gain than the EBM material. XRD and TEM/EDS analyses indicated the formation of rutile-TiO2/(α-Al2O3 + rutile-TiO2)/amorphous-Al2O3 sequence of phases. In EBM a coarse crystalline layer rich in aluminium, oxygen and a small amount of sulphur was found. The higher content of sulphur was in the scale bottom intermixed with amorphous alumina.

Dual-phase metal materials can usually take into account the advantages of both phases, but the heterogeneity of dual-phase properties will cause flow instability. Therefore, it is difficult to further improve the microstructure and properties of Nb–Si–Ti based alloys containing ductile Nbss and hard silicides through hot working. Here, we propose a method for interface modification by precipitating an intermediate phase and forming a core-shell-like structure with silicides. A novel near core-shell structure (β-Nb 5 Si 3 /Nb 4 FeSi) is obtained in Nb–Si–Ti based alloy by deep cryogenic quenching and annealing. The precipitation of Nb 4 FeSi is closely related to stacking faults, where high-density stacking faults can develop into the nanotwins during annealing at 1200 °C. In addition, two types of nanoprecipitation behaviors are observed in the Nbss and β-Nb 5 Si 3. The nanoscale plate-like δ-Nb 11 Si 4 is precipitated along the [100] Nbss and [010] Nbss in the Nbss matrix, while the precipitation of granular Nb 4 FeSi from β-Nb 5 Si 3 satisfies (1 ‾ 10) β //(0 1 ‾ 0) Nb4FeSi. In addition to the twinning induced plasticity of Nb 4 FeSi (shell), a phase transformation from β-Nb 5 Si 3 to α-Nb 5 Si 3 and Nbss that occurs within the core-shell structure is beneficial for the hot forming of the alloy. [Display omitted] [ABSTRACT FROM AUTHOR]

The effect of Sn alloying (0.5, 1.0, 2.0 wt%) on microstructure and corrosion behavior of dilute Mg-2Zn-xSn-0.5Ca rolled sheets is illuminated. The corrosion resistance first increases and then decreases with raising Sn content. The alloy with 1 wt% Sn shows the lowest corrosion rate of ∼2.1 mm/y, decreased by ∼63 % compared with Sn-free alloy. Although nobler MgSnCa phase is formed after alloying, more protective oxide film containing SnO 2 is also formed, which effectively hinders localized corrosion. However, at 2 wt% Sn addition, detrimental effect of MgSnCa overwhelms positive effect of Sn on film, thus deteriorating corrosion resistance. [Display omitted] • Sn addition reduces susceptibility to pitting corrosion of dilute Mg-Zn-Ca alloy. • Sn addition facilitates the formation of Sn-containing protective oxide film. • Sn preferentially binds to Ca to form blocky MgSnCa phase with nobler potential. • Corrosion rate reaches minimum at 1 % Sn and oxide film dominates corrosion behavior. • Corrosion rate increases at 2 % Sn and galvanic corrosion of MgSnCa plays chief role. [ABSTRACT FROM AUTHOR]

In this study, titanium aluminides comprising of Ti45Al5Nb0.5Si (TiAl-1), Ti45Al5Nb5Si (TiAl-2) and Ti45Al5Nb10Si (TiAl-3) were developed through laser direct energy deposition (LDED) with Nd-YAG laser under optimized process parameters. The microstructure of TiAl-1 consists of α 2 +γ phase mixtures. Addition of 5 wt% and 10 wt% Si results in the formation of silicides in addition to γ and α 2 phases. A thorough kinetics of cyclic oxidation (from 700°C to 900°C in air) demonstrates that with an increase in Si concentration the activation energy of oxidation increases from 227.99 kJ/mol (TiAl-1) to 337.55 kJ/mol (TiAl-3). The mechanism of oxidation has been established. • Cyclic oxidation study of Ti45Al5Nb0.5Si, Ti45Al5Nb5Si and Ti45Al5Nb10Si. • Ti45Al5Nb10Si shows superior oxidation resistance as compared to the other two. • Presence of higher Si promotes the formation of Al 2 O 3 by increasing Al activity. • In the cross-section there is formation of compositionally graded oxide scale. [ABSTRACT FROM AUTHOR]

• The electrochemical and corrosion behaviour of NixAly alloys is complex. • The behaviour depends on Ni/Al-ratio, microstructure, pH of solution, and passivation tendency. • Single-phase alloys are more corrosion resistant than multi-phase alloys. • Uniform and localized corrosion operate, with pitting corrosion being the dominating mode. Electrochemical and corrosion behaviour of as-cast NixAly intermetallic alloys (Ni25Al75, Ni40Al60, Ni50Al50 and Ni75Al25 in at. %) is investigated and compared with commercially pure extruded/tempered Al and wrought Ni in pH 2, 6 and 12 buffered solutions. Different microstructures among the NixAly alloys are obtained, from single- to multi-phase systems. The electrochemical and corrosion behaviour of the NixAly intermetallic alloys is complex and depends on the Ni/Al-ratio, the microstructure, the pH value of the solution, and the passivation tendency. Three corrosion types are found to be operating, uniform corrosion, localised/pitting corrosion and intergranular corrosion, with pitting corrosion being the dominating type. [ABSTRACT FROM AUTHOR]

Mechanically alloyed composite powders with equiatomic Fe–Al stoichiometry and with the addition of 5, 10, 20 and 30 vol% of B were subjected to consolidation. For this purpose, hot-pressing at 800 °C under the pressure of 7.7 GPa for 180 s was applied. A reference FeAl sample was prepared using the same procedure as these from the composite powders. The produced bulk materials were investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy as well as characterised by hardness, density and open porosity measurements. For the compositions containing 5, 10 and 20% of B, it was possible to obtain composites with the nanocrystalline FeAl intermetallic matrix reinforced with homogenously distributed fine boron particles. For the material containing 30% of B, the boron particles were distributed in a two-phase matrix consisting of the dominant nanocrystalline FeAl intermetallic and minor amorphous phases. The density of the composite samples is in the range of 5.31 ÷ 4.57 g/cm3, which is lower than that of the FeAl reference sample, and decreases with the increase of B content. The hardness of the composite samples is in the range of 10.75 ÷ 12.1 GPa, is higher than that of the intermetallic FeAl reference sample (9.84 GPa), and increases with the increase of B content. To the best of our knowledge, the FeAl-B composites with nanocrystalline intermetallic matrix were produced for the first time. • This is the first production of bulk nanocrystalline matrix FeAl–B composites. • The hardness of the composites is of 10.75 ÷ 12.1 GPa, depending on B content. • The hardness of the composites is higher than that of nanocrystalline FeAl alloys. • The density of the composites is of 5.31 ÷ 4.57 g/cm3, depending on B content. • The density of the composites is lower than that of nanocrystalline FeAl alloy. [ABSTRACT FROM AUTHOR]

Twelve rare-earth ruthenium indides were synthesized by a two-step reaction and their crystal structures were determined by single-crystal X-ray diffraction. R 3 Ru 1-x In 3 (Pbam , oP 28) and R 16 Ru 5 In 14 (P 2/ m , mP 35) crystallize with new structure types whereas R 39 Ru 12-x In 35 (Pbam , oP 172) and R 8-x Ru 3 In 7+x (Pmma , oP 36) present occupation variants of Nd 39 Ir 10.98 In 36.02 and Y 5 Cu 5 Mg 8 structures, respectively. The new indides are built of two different layers alternatively stacking along the shortest unit cell axis. The first layer is formed exclusively of rare-earth atoms while the second layer is built of ruthenium and indium thus displaying RIn and RRu fragments of CsCl type and RIn 2 and RRu 2 fragments of AlB 2 type. • 16 new rare-earth ruthenium indides synthesized by a two-step reaction. • Crystal structures were studied by single-crystal and powder XRD. • The compounds are built of two layers stacking along the shortest axis. • Four new types of structure are described. [ABSTRACT FROM AUTHOR]

It is commonly agreed that the α 2 phase in γ(TiAl)-based alloys is quite difficult to deform plastically especially by order twinning. In the present study, for the first time we report deformation twinning in the α 2 phase in a nearly-lamellar two-phase γ-TiAl alloy investigated by electron microscopy. Diffraction pattern and high-resolution images indicate that the twinning plane is (20 2 ¯ 1) and the twinning direction is [ 10 14 ¯ ] , which is essentially analogous to what has been observed in disordered hexagonal structures. The twinning and anti-twinning mechanisms are interpreted. The twinning is a combined result of superpartial dislocation glide activated by the dissociation of <2 c + a > type superdislocation, accompanied by atomic shuffling and short-range diffusion which is facilitated by the anti-structural bridges diffusion mechanism during high-temperature compression. The appearance of deformation twinning in the α 2 phase can play an important role for the excellent mechanical properties of high Nb containing TiAl alloys, which is of great importance for the further development of γ-TiAl alloys. • Deformation twinning of α 2 phase is firstly observed in a two-phase γ-TiAl alloy. • The twinning system is similar to that observed in disordered α structure. • Twinning and anti-twinning elements are revealed. • Atomic shuffling and short-range diffusion are responsible for deformation twins. [ABSTRACT FROM AUTHOR]

• Mo/Re duplex layer is electrodeposited on the Nb-Ti-Si based alloy. • The Re layer can improve the electrodeposition of Mo. • Porous structure of MoSi 2 is due to the oxides in the as-deposited Mo layer. • The MoSi 2 /ReSi 2 /NbSi 2 compound coating shows perfect protection for the substrate. MoSi 2 /ReSi 2 /NbSi 2 compound coating has been successfully prepared on the Nb-Ti-Si based alloy through electrodeposition and halide activated pack cementation (HAPC) process. Optimization of electrodeposition process, the microstructural evolution and oxidation resistance of the compound coating were investigated. Re is beneficial to the electrodeposition of Mo and then improves the integrity and adherence of MoSi 2 layer. The porous structure and limited thickness expansion of MoSi 2 layer should be attributed to the oxides in the electrodeposited molybdenum layer. Remarkably, the substrate could be effectively protected by the compound coating at 1150 °C due to the formation of a dense scale. [ABSTRACT FROM AUTHOR]

Abstract Nanocrystalline hydrogen storage La 1.5 Mg 0.5 Ni 6.5 Co 0.5 alloy was obtained by mechanical alloying and heat treatment (850 °C/0.5 h). The A 2 B 7 phase is dominant in so synthesized material. Concentration of AB 5 phase is close to 3 at. % and is 2.6 times lower than that in Co-free La 1.5 Mg 0.5 Ni 7 alloy. The La 1.5 Mg 0.5 Ni 6.5 Co 0.5 powder fraction of 20–50 μm was encapsulated with thin (0.48 μm thick), amorphous nickel by magnetron sputtering. The electrochemical charge/discharge multicycling of powder composite electrodes was carried out in view of material potential usefulness as electrode material for Ni/MH x batteries. Partial substitution of Ni by Co in La 1.5 Mg 0.5 Ni 7 nanocrystalline alloy is prone to increase of electrode discharge capacity (up to 14%) and enhances its activation (strong decrease of N max cycle and simultaneous increase of Q N max ). On the other hand, Co addition worsens corrosion degradation behavior, but the corrosion resistance can be improved (≈30%) by the application of amorphous nickel coating. Finally, Co modified La 1.5 Mg 0.5 Ni 7 nanocrystalline alloy reveals 15% greater exchange current density of H 2 O/H 2 system and improved hydrogen diffusivity compared to the reference, nanocrystalline Co-free La 1.5 Mg 0.5 Ni 7 hydrogen storage material. Highlights • Nanocrystalline La 1.5 Mg 0.5 Ni 6.5 Co 0.5 hydrogen storage alloy was produced by MA. • Co-addition increases capacity, enhances activation but worsens corrosion resistance. • Co-addition improves hydrogen sorption kinetics and its diffusivity in the alloy. • PVD sputtered, 0.48 μm thick Ni layer inhibits alloy corrosion decay in KOH by 30%. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Oxidation barrier Fe-Cr-silicide coating formed on strategic Nb-18.7Si-Ti/Zr alloys. • Comparative cyclic oxidation testing of uncoated and coated alloys conducted in air. • Coating prevents oxidation, dimensional degradation in air at temp. of 800–1400 °C. • Mechanism of oxidation protection and characteristics of oxide scale are discussed. • The coating is indispensible for critical high-temperature applications of alloys. Abstract The Nbss/Nb 3 Si-Nb 5 Si 3 alloys exhibit good high-temperature strength and creep resistance, and are candidate high-temperature materials for hypersonic aerospace applications. However, their poor oxidation resistance necessitates the application of protective coatings.The present study examines the comparative cyclic oxidation behavior of uncoated and Fe-Cr modified slurry silicide coated Nb-18.7Si, Nb-18.7Si-5Ti and Nb-18.7Si-5Zr (in at.%) alloys in air at temperatures between 800–1400 °C. The uncoated samples showed extensive loose-scale formation from the initial stages of oxidation. On the other hand, the protective multi-phase oxide scale formed on the coating surface prevented dimensional degradation for at least 5–7 h at high temperatures of 1400 °C. [ABSTRACT FROM AUTHOR]

Abstract A relatively simple approach based on mixing WC and iridium powders, followed by heating to 1300–1600 °C in inert atmosphere, was proposed to synthesize refractory intermetallics in the tungsten – iridium system. The peculiarities of the solid-state interaction in the WC-Ir system were studied within the 1000–1600 °C temperature range using a set of modern analytical techniques. Intensive solid-state interaction in the WC – Ir system starts at 1300 °C. It was stated that this interaction can be described by two stages in the 1300–1600 °C temperature range. The first stage is the formation of Ir-rich disordered W x Ir 1-x solid solution with constant average composition W 0.265 Ir 0.735. The second stage is the interaction of the obtained W x Ir 1-x solid solution with residual component (Ir or WC) that leads to the shift of the W x Ir 1-x phase composition on one side or the other in dependence on type of residual component. No ordered intermetallic phases are formed in the 1300–1600 °C temperature range. In the course of the solid-state reaction, free carbon is released as graphite-like phase on the surface of the intermetallic product. Graphical abstract Image 1 Highlights • Intensive interaction of Ir with WC starts at relatively low temperature (1300 °C). • Products of interaction are W x Ir 1-x solid solution and free carbon. • The steady-state W 0.265 Ir 0.735 phase is formed at the first stage of interaction. • At the second stage, the W x Ir 1-x composition shifts to homogeneity boundaries. [ABSTRACT FROM AUTHOR]

Abstract In/Ga elements were doped in GaSb/InSb crystals respectively, and their thermoelectric performances were studied. The crystals had cubic zinc blende structure with change in lattice parameters. The charge transfer occurred between all the three (In, Ga and Sb) elements when In was doped with GaSb. Whereas in Ga doped InSb crystals, the charge transfer occurred only among Ga and Sb elements. In/Ga doped GaSb/InSb crystals exhibited degenerate and non-degenerate electrical properties, respectively. Optical modes of phonon vibrations were present, and their transverse mode was dominant over longitudinal mode in all the samples. The thermoelectric figure of merit (ZT) of In doped GaSb crystals were low because of their low power factor and high thermal conductivity. The highest power factor (59.5 μW/cmK2) and ZT (0.56) at 573 K were achieved by Ga doped (1 × 1021/cm3) InSb crystal. The ZT 0.56 at 573 K is thus far the highest among other reported values of InSb crystals. Highlights • In/Ga elements were doped with GaSb/InSb and their TE properties were studied. • GaSb:In and InSb:Ga crystals showed degenerate and non-degenerate electrical properties. • The power factor of InSb:Ga21 sample recorded to be 5.95 mW/mK2 at 573 K. • The thermal conductivities of GaSb and InSb were reduced up to 43 and 39% at 300 K. • Ga doped (1 × 1021) InSb achieved the highest ZT of 0.56 at 573 K. [ABSTRACT FROM AUTHOR]

Abstract Crystalline phases formed in stoichiometric Zr 9 Ni 11 and Hf 9 Ni 11 have been studied by perturbed angular correlation (PAC) spectroscopy, XRD and TEM/SAED measurements. In Zr 9 Ni 11 , the phases Zr 9 Ni 11 (∼ 89%) and Zr 8 Ni 21 (∼ 11%) have been found at room temperature from PAC measurements. At 773 K, Zr 9 Ni 11 partially decomposes to Zr 7 Ni 10 and at 973 K, it is completely decomposed to ZrNi and Zr 7 Ni 10. In Hf 9 Ni 11 , a predominant phase (∼ 81%) due to HfNi is found at room temperature while the phase Hf 9 Ni 11 is produced as a minor phase (∼ 19%). No compositional phase change at higher temperature is found in Hf 9 Ni 11. Phase components found from XRD and TEM/SAED measurements are similar to those observed from PAC measurements. Electric field gradients in Zr 9 Ni 11 and Hf 9 Ni 11 have been calculated by density functional theory (DFT) using all electron full potential (linearized) augmented plane wave plus local orbitals [FP-(L)APW+lo] method in order to assign the phase components. Graphical abstract Left: Results of experimental and theoretical electric field gradients in Zr 9 Ni 11 and Hf 9 Ni 11. Right: Three non-equivalent crystallographic sites of Hf in Hf 9 Ni 11 (top) and variation of electric field gradients with temperature (bottom). fx1 Highlights • Zr 9 Ni 11 and Hf 9 Ni 11 have been studied by PAC, XRD and TEM/SAED. • Multiphase components have been found in stoichiometric Zr 9 Ni 11 , Hf 9 Ni 11. • Zr 9 Ni 11 transforms to Zr 7 Ni 10 Ni at 773 K while Hf 9 Ni 11 remains stable up to 873 K. • Experimental results of electric field gradients agree with calculated results by DFT. • Weak temperature dependence of EFGs have been found in Zr 9 Ni 11 and Hf 9 Ni 11. [ABSTRACT FROM AUTHOR]

Abstract Nb 3 Al superconductors with high superconducting performance are of interest as potential materials for using in high magnetic fields. The phase formation mechanism plays a vital role in preparing high quality Nb 3 Al superconductor, especially with better superconducting transition temperature (T c). In this work, the phase evolution of Nb Al system during mechanical alloying and subsequent sintering process was studied, and the corresponding kinetics mechanism of Nb 3 Al phase formation was investigated in detail. It was found that the Nb 3 Al phase can be formed through two different routes: one is reaction between Nb 2 Al and Nb, the other is transformation from Nb Al supersaturated solid solution (Nb(Al) ss) directly. Mechanical alloying promotes the transformation of Nb Al pre-alloyed powders from local Nb Al amorphous to Nb(Al) ss , controlling the different formation routes of Nb 3 Al phase. According to the kinetics calculation of the Nb 3 Al phase formation during sintering process, the values of activation energy (E) for the reaction between Nb 2 Al and Nb forming Nb 3 Al is higher than that for the transformation from Nb(Al) ss to Nb 3 Al in the initial stage, but decreases sharply with the reaction going on. Moreover, Nb 3 Al bulk synthesized via reaction between Nb 2 Al and Nb obtained a higher value of T c (about 15.8 K) compared with the Nb 3 Al bulk synthesized via Nb(Al) ss. The results in our work suggest that the phase formation mechanism of Nb 3 Al during mechanical alloying and subsequent sintering process actually influence their final superconductivity performance and can give an effective guide for optimizing the technique of preparing Nb 3 Al superconductors. Graphical abstract Image 1 Highlights • Two formation routes of Nb 3 Al phase are found during mechanical alloying and subsequent sintering. • The formation of Nb 3 Al phase is dominated by interface reaction and random nucleation. • Nb 3 Al bulk synthesized via reaction between Nb 2 Al and Nb obtained a higher value of T c. [ABSTRACT FROM AUTHOR]

Abstract The influence of Ni on the size and twinning of primary Cu 6 Sn 5 crystals in Sn-0.7Cu-0.05Ni and Sn-xCu (x = 0.7, 0.9, 1.1) (mass%) solder joints is studied using synchrotron radiography and SEM-based EBSD. It is shown that the Ni addition does not cause significant refinement of primary Cu 6 Sn 5 if the alloy is fully melted. However, for peak temperatures ≤250 °C relevant to industrial soldering, primary Cu 6 Sn 5 are not completely melted in Sn-0.7Cu-0.05Ni and there are 10–100 times more numerous and smaller crystals than in Sn-0.7Cu. X-shaped Cu 6 Sn 5 crystals with an angle of ∼70° commonly formed in Sn-0.7Cu-0.05Ni/Cu joints and are shown to be penetration twins. This type of growth twinning was only found in partially melted samples, both in Sn-0.7Cu-0.05Ni/Cu joints and binary Sn-1.1Cu alloy. The frequency of twinned crystals was significantly higher in Ni-containing solders. The results are discussed in terms of the influence of Ni on the Cu 6 Sn 5 liquidus slope and on the lattice parameters of (Cu,Ni) 6 Sn 5. Graphical abstract Image 1 Highlights • Ni solute itself is shown to be ineffective in refining primary Cu 6 Sn 5. • The size of primary Cu 6 Sn 5 after solidification strongly depends on the original size in the original solder ball/paste before melting. • Growth twinning occurs in primary Cu 6 Sn 5 and is promoted by Ni additions. • The changing lattice parameters of Cu 6 Sn 5 by Ni additions facilitate coexisting { 10 1 ¯ 2 } and { 10 1 ¯ 1 } twin planes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Solid-state reaction of TaC with Ir leads to the formation of TaIr 3 intermetallics. • TaIr 3 -based material displays good ablation resistance under extreme conditions. • Microstructure and composition are responsible for good ablative behavior. Abstract The solid-state interaction of TaC with Ir within the 1000–1600 °C temperature range leads to the formation of TaIr 3 intermetallics. The durability of the TaIr 3 -based system with a silicon additive was studied under extreme environmental conditions. The TaIr 3 -based material displays satisfactory ablation resistance at 2000 °C in air in arc-jet. The post-test microstructural and XRD analysis of the developed material allowed us to propose the role of different constituents of the Ta – C – Ir – Si system. The iridium-containing phases play the most significant role in favorable ablation behavior of the developed system. [ABSTRACT FROM AUTHOR]

Highlights • Shot peening produced a deformation zone on the top of a TiAl based alloy. • γ/α 2 lamellar structure was collapsed and grains refined in the deformation zone. • Shot peening catalyzed formation of a submicron-thick α-Al 2 O 3 film. • The prior Al 2 O 3 formation prohibited Ti of the alloy from oxidation at 900 °C. Abstract Shot peening, although generally accepted as a useful surface treatment method to improve oxidation resistance of Ni-, Co- and Fe-based alloys, has been less applied to TiAl based alloys. This work shows that a shot peening treatment converts the Ti-45Al-2Nb-2Mn-1B alloy from thermally growing TiO 2 -Al 2 O 3 mixed oxides to an exclusive Al 2 O 3 in air at 900 °C. The basic reason for this is that the shot peening catalyzes formation of an α-Al 2 O 3 thin film, which prevents Ti of the alloy from oxidation at the high temperature. The slow oxidation of the shot-peened alloy mitigates the degradation of typical γ/α2 lamellar microstructure. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Nanometer scale Cu-rich precipitates behaved as distinct electrochemical entities. • They contributed to the surface Cu coverage of the deoxidised alloy. • The surface Cu coverage was increased for long-aged samples. • Thicker but more defective TCP coatings formed on long-aged samples. • TCP coatings formed on long-aged samples had low protective properties. Abstract The influence of 2024 aluminium alloy microstructure on the protective properties of trivalent chromium process (TCP) coatings was studied: samples aged at 190 °C were analysed by comparison to a T3 state. The surface Cu coverage after deoxidation was higher for long-aged samples because nanometer scale Cu-rich precipitates formed during ageing behaved as distinct electrochemical entities and contributed to the formation of copper deposits. The growth mechanisms and kinetics of TCP coatings were directly related to the surface Cu coverage: thicker but more defective TCP coatings formed on long-aged samples leading to the lowest anti-corrosion properties. [ABSTRACT FROM AUTHOR]

We report new insights into the solder wettability degradation of Sn thin films on Cu under 155 °C isothermal ageing. A multiscale wettability degradation model was established, reflecting quantitatively the surface oxidation and interfacial intermetallic compound (IMC) growth, on the basis of solder wetting behaviour. The thermal oxidation of Sn exhibited heterogeneous inward thickening, lateral expanding and outward platelet-like growth, forming nanocrystalline, oxygen-deficient SnO 2 with pronounced voiding/cracking propensity. Unlike a commonly held belief that the initial wettability loss is due to surface-exposing and oxidation of IMCs, it was found from dual combined effects of inward surface oxidation and outward IMC growth. [ABSTRACT FROM AUTHOR]

The effects of surface abrasion on microstructure and pitting corrosion of 2297 Al-Li alloy were investigated. Statistical analysis reveals that surface abrasion alters surface roughness and induces partial dissolution of intermetallic particles. A smoother surface finish reduces the population density and the average size of AlCuMnFe particles, due to enhanced dissolution of AlCuMnFe particles. All abraded samples undergo pitting corrosion, and surface layer dissolution (except pitting) is not observed. Smoother surface has lower pitting susceptibility and better corrosion resistance than the rougher surface. The intermetallic particles significantly affect pitting corrosion of 2297 Al-Li alloy, while surface roughness has small influence. [ABSTRACT FROM AUTHOR]

A novel lamellar NiAl nanochannel with NiAl lamellae and nanochannels was fabricated from directionally solidified NiAl–Cr(Mo) eutectic alloy by selective phase dissolution. The optimum potential for the selective dissolution was at 1.14 V SHE . Results revealed that the Cr(Mo) phase in the NiAl–Cr(Mo) eutectic was removed completely, and the lamellar nanochannel was revealed during the selective dissolution. The width of the nanochannel was 620 nm, and the depth approached 83.6 μm; both can be tuned by controlling the growth rate and dissolution time. These highly oriented NiAl architectures with narrow nanochannels can be used to fabricate multilayered devices/capacitors. [ABSTRACT FROM AUTHOR]

Nanocrystalline La 1.5 Mg 0.5 Ni 7 alloy has been synthesized by mechanical alloying and heat treatment (850 °C) and a 20–50 μm fraction of its particles has been encapsulated with three kinds of Ni-based coatings: (i) electroless Ni P, 1 μm thick, (ii) magnetron sputtered Ni, 0.087 μm thick and (iii) magnetron sputtered Ni, 0.29 μm thick. The electrochemical charge/discharge multicycling of powder composite electrodes has been carried out in view of material potential usefulness for Ni/MH x batteries. The nanocrystalline La 1.5 Mg 0.5 Ni 7 alloy exhibits four times lower capacity fade as compared to a microcrystalline LaNi 5 reference compound. Modification of La 1.5 Mg 0.5 Ni 7 particle surface with comparatively thick layer of electroless Ni P coating deteriorates electrode corrosion behavior and worsens kinetics of hydrogen electrosorption due to unsatisfactory adhesion of the coating to the Mg-containing substrate. Corrosion protection of the La 1.5 Mg 0.5 Ni 7 nanomaterial by magnetron sputtered Ni films depends on average film thickness. Relatively thick (0.29 μm) sputtered Ni film limits corrosion degradation and stabilizes exchange current density of H 2 O/H 2 system. Particle modification by Ni encapsulation does not affect the hydrogen diffusivity. Effective diffusion coefficient of hydrogen for La 1.5 Mg 0.5 Ni 7 nanocrystalline material, irrespectively of surface modification, is close to 2·10 −10  cm 2 s −1 . [ABSTRACT FROM AUTHOR]

The precipitation behaviors of β o (ω) phases are investigated in order to understand the effects of deformation on the microstructural stability during thermal exposure. Deformation can promote the precipitation of the β o (ω) phases not only at the lamellar boundaries but within the lamellar colonies. The higher exposed temperature and lager engineering strain are in favor of the precipitation of the β o (ω) phases. Four different ω o variants are identified at the β o regions of the deformed samples, indicating the residual stress induced by deformation cannot change the preferential formation of ω o variants during exposure. Diffusion during the parallel decomposition promotes the formation of ω o phase by making Nb enriched in the remaining α 2 laths. During the growth of ω o grains, W is excluded and enriched in local regions of the α 2 laths, leading to the formation of β o phase. The residual stress of the deformed samples is measured by the hole-drilling method. After deformation, the absolute value of residual stress comes to a peak value and then gradually decreases during exposure. The Vickers hardness shows a similar varying trend with the residual stress. Deformation can significantly decrease the microstructural stability and promote the precipitation of the β o (ω) phases. [ABSTRACT FROM AUTHOR]

The heat capacity of ε (Fe 5 Al 8 ) was determined between 1395 and 1455 K by DSC measurements. The homogeneity ranges of the intermetallic phases ζ (FeAl 2 ), η (Fe 2 Al 5 ) and θ (Fe 4 Al 13 ) in the temperature range between 1073 and 1435 K were determined using WDS measurements on annealed and quenched samples in the composition range between 56.0 and 75.3 at.% Al. The solidus and liquidus temperatures of all samples were determined using DTA. A CALPHAD-type assessment of the Al-Fe system was done based on latest experimental results on heat capacity of the intermetallic phases. [ABSTRACT FROM AUTHOR]

Based on results from XRD, SEM/EDX and DTA, a new version of the Sb-Sn phase diagram was established that includes the Sb 3 Sn 4 phase with R 3 ¯ m space group and a commensurately ordered superstructure that can be derived from stacking seven layers of the conventional rhombohedral SbSn cell. The close structural relationships between these two structures have so far caused Sb 3 Sn 4 to be overlooked in most works. The phase Sb 2 Sn 3 , which had been established in some phase diagram versions without clear proof or structural description could be ruled out. Seemingly diverging literature results can now be explained in a consistent way based on a comprehensive literature review in part I and the new data from the present work, part II. [ABSTRACT FROM AUTHOR]

For the manufacturing of low pressure turbine blades, titanium aluminides are used as structural materials, among them the alloy Ti-43.5Al-4Nb-1Mo-0.1B (at.-%) known as TNM™ alloy. In this study, laser metal deposition (LMD) was investigated as a potential technology to repair defective, damaged or worn blades, and process conditions were successfully optimized. However, post-process heat treatment is required to optimize the microstructure. In this work, different annealing treatments and the resulting microstructures were characterized for bulk LMD samples as well as for investment cast reference samples. Annealing temperatures were selected from 1245 to 1290 °C. The results show that annealing at 1290 °C for a duration of 60 min with subsequent furnace cooling can be used so that the LMD and cast micro-hardness nearly match, albeit with significant differences in microstructure. Nonetheless, yield strength mismatch can be mitigated and LMD can qualify as prospective additive repair technology, but also as a manufacturing technology for functional TiAl parts. [ABSTRACT FROM AUTHOR]

Using first-principles calculations method based on density functional theory (DFT) with the Perdew–Burke–Ernzerhof (PBE) implementation of the generalized gradient approximation (GGA), we investigate the structural, elastic and thermodynamic properties of gold-copper intermetallic compounds (Au–Cu ICs). The calculated lattice parameters are in excellent agreement with experimental data. The elastic constants show that all the investigated Au–Cu alloys are mechanically stable. Elastic properties, including the shear modulus, Young's modulus, Poisson's ratio and Pugh's indicator, of the intermetallic compounds are evaluated and discussed, with special attention to the remarkable anisotropy displayed by Au–Cu ICs. Thermodynamic and transport properties including the Debye temperature, thermal conductivity and melting point are predicted from the averaged sound velocity and elastic moduli, using semi-empirical formulas. [ABSTRACT FROM AUTHOR]

High-temperature mechanical behavior and microstructure evolution during hot deformation of an as-cast β-solidified Ti-43.2Al-1.9V-1.1Nb-1.0Zr-0.2Gd-0.2B (at.%) alloy were studied. Phase transformation temperatures and associated phase fields (α 2 + γ, α + γ, α, and α + β) were established by Thermo-Calc calculations, dilatometry, differential scanning calorimetry and microstructure analysis of specimens annealed at different temperatures. The as-cast alloy was subjected to uniaxial compression at temperatures from 900 to 1250 °C and strain rates in the range 0.001–1 s −1 . Two temperature intervals with different mechanical behavior were found: the first corresponded to the α 2 +γ phase field (900–1100 °C), where the microstructure was mainly lamellar, and the second covered the α + γ, α, and α + β phase fields (1100–1250 °C), in which the α phase dominated. In the first interval, mechanical behavior was typical for lamellar structure and was associated with transformation of lamellar structure into globular one via dynamic recrystallization/spheroidization processes. In the second interval, the mechanical behavior was similar despite the changes in phase composition and the controlling process of the microstructure evolution was dynamic recrystallization. In the α + γ phase field deformation accelerated the γ→α transformation. Deformation in all phase fields resulted in microstructure refinement which, in turn, induced superplasticity under certain temperature-strain rate conditions. To determine the most suitable conditions for working of the alloy, processing maps were constructed. Two domains with high power dissipation efficiency (η > 0.5) were found. The first domain was located at the top of the α 2 +γ and the bottom of the α+γ phase fields with the peak efficiency of 0.57 at ∼1100 °C and 0.05 s −1 . The second domain belonged to the α + β phase field with the maximum efficiency of 0.74 at ∼1250 °C and 0.5 s −1 . The relationships between mechanical behavior and microstructure after deformation were discussed. [ABSTRACT FROM AUTHOR]

A B-modified silicide coating on Nb-Si based alloy was prepared by the method of pack cementation. The oxidation resistance of the B-modified silicide coating was studied in the pest-oxidation temperature range (from 650 °C to 850 °C). Oxidation experiments show that the samples coated with B-modified silicide coating maintain low-rate oxidation and suffer from no pest oxidation at all experimental temperatures. The preferential oxidation of Ti and Si can suppress the formation of Nb 2 O 5 . Besides, the borosilicate scale with high fluidity can seal the cracks and pores in the scale. Thus, the occurrence of pest catastrophe is avoided. [ABSTRACT FROM AUTHOR]

The isothermal phase diagram of the Co-Cr-Mn ternary system at 700 ℃ was experimentally determined via field-emission electron probe microanalysis/wavelength dispersive X-ray spectrometry and electron backscatter diffraction analyses. Three-phase regions of αCo (para) + βMn+ σ and αMn+ βMn+ σ were confirmed via equilibrated microstructures; however, three-phase microstructures related to αCo (para) + εCo+ σ and α'+ (Cr)+ σ were not observed in our study. The three-phase region of αCo (para) + εCo+ σ was estimated to be very narrow because the phase boundaries between the αCo (para) and εCo phases were different within 2 at% for the Co, Cr, and Mn compositions. Furthermore, the α' phase, presumed to be a nitride, was not observed in the microstructure equilibrated under a strictly controlled high-purity Ar gas (99.999%) atmosphere. The σ phase indicated a wide single-phase region similar to a previous study reported at temperatures between 900 ℃ and 1200 ℃. The αMn phase, which is stable below 727 ℃ in the Cr-Mn binary system and below 900 ℃ in the Co-Mn binary system, had a large Co solubility of 9.8 at% in the Co-Cr-Mn ternary system. The composition dependences on the lattice constants of the σ phase in the Co-Cr-Mn ternary system were examined via X-ray diffraction analysis; this analysis showed that the lattice constants a and c changed significantly with increasing Mn composition in the Co and Mn substitution, while the lattice constant of a was constant and c was slightly increased by increasing Mn composition in Cr and Mn substitution. From first-principles calculations, it was deduced that increases or decreases in bonding lengths between the nearest atoms occupying the five sublattice sites were associated with small changes in the lattice constant when Mn replaced Cr. The hardness of the σ phase decreased with increasing c / a , and the hardness in the crystal orientation of (100) was more dependent on the Mn composition than that in the crystal orientation of (001). • The phase equilibrium of the Co-Cr-Mn ternary system at 700 ℃ was experimentally determined. • The σ phase in the Co-Cr-Mn ternary system was confirmed by a wide single-phase region. • The variation of the lattice constants of the σ phase showed different tendencies in the Cr/Mn and Co/Mn substitution. • The micro-Vickers hardness of the σ phase depends not only on the c/a but also on the crystal orientations. [ABSTRACT FROM AUTHOR]

Ti–Al intermetallic alloys have a number of advantages for the manufacture of aviation and car details. The use of these alloys is limited by their oxidation at high temperatures, which is associated with structural features and the presence of micro and nanosized grains. In such materials, grain boundary diffusion of oxygen can be active, which contributes to the acceleration of oxidation upon heating. In this paper, we present a two-dimensional model for research the diffusion which is accompanied by oxidation. The structure of TiAl is specified as symmetrically alternating grains with a clear separation of boundaries and triple junctions between them. Diffusion and chemical properties of grains and boundaries are different. The problem is formulated in a two-dimensional formulation and solved numerically. The influence of changes in the composition over time on the penetration of oxygen is taken into account. For the convenience of numerical research and analysis of the results, dimensionless variables are used. To solve the diffusion equation, an implicit difference scheme of splitting in coordinates is used. The equations of chemical kinetics are solved using an algorithm similar to the implicit Euler method using an iterative procedure. The results demonstrate the influence of different variants of kinetic regimes on the concentration distribution and integral concentrations of reagents and oxides. • A two-dimensional model is used to analysis the oxidation of TiAl alloy. • Grain boundary diffusion and oxidation are modeled for isothermal conditions. • Two kinetic regimes are revealed for the case of oxides accumulation in surface layer and for the case of predominant oxidation along grain boundaries. • It is detected that concentration dependence of diffusion coefficient affects the oxidation dynamics. [ABSTRACT FROM AUTHOR]

The inhibitive effect brought by benzotriazole (BT) on AA2024 in neutral aerated sodium chloride solutions was evaluated using electrochemical techniques (large and micro scale polarization curves, electrochemical impedance spectroscopy) and surface analyses (ToF-SIMS and XPS) in the view of its incorporation into protective coatings to provide self-healing ability. It was found that the formation of a benzotriazole-based film concerns the entire surface, covering the aluminium matrix and the intermetallic particles. The presence of inhibitor in the electrolyte is required to preserve the inhibitive layerstability. The film formation is favoured by the presence of chloride ions in the inhibitor-containing solution. [ABSTRACT FROM AUTHOR]

Knowledge of the ideal shear strength of solid single crystals at finite temperatures is of fundamental importance. It is mainly determined by the molecular dynamics simulations. However, thus obtained results are strongly dependent on the employed empirical potentials. In the present work, two theoretical models for the temperature-dependent ideal shear strength of single crystals are established based on the Frenkel's classical theory and the energy view. To test the established models, the ideal shear strengths of β-NiAl and γ-Ni 3 Al alloys are calculated from 0 K to the melting point and compared with the results reported in the literature. The study shows that both shear modulus and ideal shear strength firstly remain approximately constant and then decrease almost linearly as temperature changes from 0 K to melting point. However, the ideal shear strength has stronger temperature dependence than the shear modulus. [ABSTRACT FROM AUTHOR]

The oxidation resistance in air of Ti-48Al-2Cr-2Nb, Ti-48Al-2Nb-0.7Cr-0.3Si, Ti-43.5Al-4Nb-1Mo and Ti-47Al-2Cr-8Nb alloys was investigated in the range of 800–1000 °C. Specimens were machined from the core of bars processed by Electron Beam Melting. Oxidation tests were performed in TGA equipment under isothermal conditions at different temperatures. The composition of the oxide layers was investigated by XRD, SEM-EDS and XPS. Layer exfoliation was observed, starting from different temperatures for the different alloys. When spallation did not happen in a significant extent the oxide layers grew according to a parabolic law. The kinetic rate constants and the activation energies were calculated. These kinetic parameters allowed to assess a rank of oxidation resistance, which can be correlated with the composition of the alloys. [ABSTRACT FROM AUTHOR]

Prior work on laser additive manufacture has shown that it is only possible to produce crack free components in TiAl when using a supplementary heat source to control the cooling rate. In this work the LENS process was used to produce crack free TiAl parts without using a secondary heat source by manipulating the laser focus position. [ABSTRACT FROM AUTHOR]

Phase stability information regarding the formation of the topologically close packed (TCP) phases is critical for the design of advanced Ni-based and Co-based superalloys that contain high concentrations of refractory elements. Isothermal sections of the Co-Ni-W, Co-Ni-Mo, Co-Ni-Nb and Co-Ni-Ta systems at both 900 °C and 800 °C were constructed for the first time from electron probe microanalysis (EPMA) and electron backscatter diffraction (EBSD) measurements on two Co-CoAl-Cr-Mo-Ni-Nb-Ta-W diffusion multiples. The new data will serve as experimental input to future thermodynamic assessments of the Co-Ni-X ternary systems in order to improve the thermodynamic databases for the design and development of advanced Ni-based and Co-based superalloys. [ABSTRACT FROM AUTHOR]

Pure Sn solder balls of initial diameter of 2 mm, having been reflow soldered on Cu substrate at 573.15 K for 1, 2 and 5 min, were subjected to furnace cooling. Upon the start of reflow, the initially spherical solder balls underwent a rapid radial spreading and wetting on Cu substrate and thus attained non-spherical geometry with a maximum height at the center whereas a minimum one at the periphery. The wetting or interfacial reaction, that would produce an even scalloped intermetallic compounds (IMCs) during isothermal reflow, resulted in the growth of dense prismatic IMC rods at the central region during cooling whereas the peripheral scalloped IMCs were not overriden by the faceted or prismatic rods during the temperature reduction procedure. Reduced interfacial heat transfer at the central interface, existence of radial isotherms and lowered supply of Cu precipitates at the peripheral interface owing to the compromised solder height have been discussed as the factors responsible for the segregated IMC morphology. The abundant precipitation of Cu and the presence of thermal gradient, sustain a screw dislocation based growth of hexagonal IMC whiskers. The increase in reflow duration is associated with the enhanced tubularity of the rods. Finite element method has been utilized to accomplish numerical simulations for heat and mass transfer in solder phase as well as for anisotropic thermal conduction at the dislocation in evolving IMC. [ABSTRACT FROM AUTHOR]

A combination of glow discharge optical emission spectroscopy sputtering and local electrochemical measurements was used to determine electrochemical changes upon brazing in a multi-layered Aluminium sheet (AA4343/AA3xxx/AA4343) with an additional low-Cu (AA3xxx) interlayer. E corr values from potentiodynamic polarization, galvanic corrosion behaviour by ZRA, microstructure and composition by SEM and TEM were investigated and compared to those obtained for sheet without the interlayer. Inward diffusion of Si from clad, and outward diffusion of Cu from core are found to degrade the corrosion properties of conventional sheet, whereas presence of interlayer reduced outward diffusion of Cu and hence improved corrosion protection. [ABSTRACT FROM AUTHOR]

Electrical and thermal transport properties of the Heusler-type alloys, Ru 2 VAl 1− x Ga x ( x = 0.0–1.0) were studied by means of the electrical resistivity, Seebeck coefficient, and thermal conductivity measurements. All studied compounds show weak metallic characteristics with a low residual resistivity ratio. In addition, the Ru 2 VAl 1− x Ga x alloys with x ≤ 0.75 show an n -type thermoelectric conduction from 10 to 300 K, while Ru 2 VGa displays p -type conduction. The estimated Fermi energy of these materials is higher than 0.5 eV, endorsing their metallic character. From the thermal conductivity study, we noticed that low-temperature thermal conductivity decreases with increasing Ga content for x ≤ 0.5 and then increases with further Ga substitution. This observation is essentially due to the change in the phonon scattering processes as a result of the substitution of heavier Ga atoms into the Al sites of Ru 2 VAl. It is important that an enhanced thermoelectric figure of merit ZT was found in Ru 2 VAl 0.25 Ga 0.75 , about seven times higher than that in Ru 2 VAl. [ABSTRACT FROM AUTHOR]

For several decades, controversial and seemingly contradicting results were published for the Sb-Sn intermetallic system, which led to the construction of different phase diagram versions. Within the investigation of the thermochemistry of Sb-Sn based systems for use as anode materials in Li-ion batteries, many of these uncertainties were resolved through the introduction of the compound Sb 3 Sn 4 (space group R 3 ¯ m , Bi 3 Se 4 prototype), whose crystal structure can be derived as a commensurate ordering from the neighboring incommensurate SbSn crystal structure (space group R 3 ¯ m , distorted NaCl type). Due to the amount of collected literature data and own analyses this work is presented as a two-part series, where Part I describes and assesses the current state of knowledge, while part II reports the new results and consistently resolves the discrepancies between earlier reports and this work. Existing literature data already show that an Sb 2 Sn 3 compound with ordered NaCl structure cannot exist due to the diverging stoichiometry. Direct experimental evidence in favor of the existence of this compound is scarce, but thermal effects that might correspond to its peritectic formation were frequently and consistently observed. Newer results point towards the existence of a compound Sb 3 Sn 4 instead of Sb 2 Sn 3 , but no crystal structure has been reported so far. Claims for further ordered phases lack the support through conclusive X-ray data. The understanding of the Sb-Sn system therefore essentially depends on understanding the complex crystallography of its intermetallic phases. [ABSTRACT FROM AUTHOR]

Stability, magnetic properties, electric field gradients and hyperfine fields of YCo 5 H x compounds were investigated by using DFT based calculations. Two computational approaches were employed in the study-ultrasoft pseudopotentials with plane waves and all-electron FP(L)APW + lo method. It was found that H atoms prefer off-centered or centered octahedral sites. Enthalpies of formation for α→β transition were calculated. Inclusion of zero-point correction reduces agreement between theoretical values of enthalpy of formation obtained from spin-polarized calculations and experimental value. Comparison of theoretical and experimental spin magnetic moments of different YCo 5 H x compounds resulted in a reasonable agreement between present theoretical results and previous experimental and theoretical data. Magnetocrystalline anisotropy energy (MAE) was calculated for intermetallic compound YCo 5 . Reasonable agreement was found between MAE obtained in the present study and the corresponding theoretical and experimental values obtained in earlier studies. [ABSTRACT FROM AUTHOR]

In this study, the solidification behavior of an intermetallic γ-TiAl based alloy, the so-called β-solidifying TNM alloy, Ti-43.5Al-4Nb-1Mo-0.1B [at.%], was investigated regarding the evolving phases, morphology and microstructure as a result of the high solidification rate during gas-atomization. By means of X-ray diffraction combined with electron back-scatter diffraction as well as at a higher resolution by transmission electron microscopy and transmission Kikuchi diffraction, conclusions regarding the ongoing processes during cooling were withdrawn. Furthermore, differential scanning calorimetry measurements on the powder condition served as supportive tool for the understanding of the microstructural development during heating of the initial state of disequilibrium. The investigations revealed a cellular/dendritic structure of the primary solidified β-grains and microsegregations along the former solidification front. The former β-grains, examined by energy dispersive X-ray spectroscopy and atom probe tomography, showed an increasing Al-content and a depletion of refractory metals when moving from the center toward the interface. Depending on the local chemical composition, the high cooling rate results in a massive type transformation of α-Ti(Al)/α 2 -Ti 3 Al- and γ-TiAl phase in the Al enriched areas, and to a martensitic transformation in the center of the retained β-phase. Furthermore, a partial suppression of the ordering reaction of the majority α-phase is detected. During annealing the microstructure evolves toward equilibrium condition, i.e. the ordering of the retained α-phase and the formation of nanolamellar γ-phase are observed. [ABSTRACT FROM AUTHOR]

The directional coefficient of thermal expansion (CTE) of intermetallics in electronic interconnections is a key thermophysical property that is required for microstructure-level modelling of solder joint reliability. Here, CTE ellipsoids are measured for key solder intermetallics using synchrotron x-ray diffraction (XRD). The role of the crystal structure used for refinement on the CTE shape and temperature dependence is investigated. The results are used to discuss the βSn-IMC orientation relationships (ORs) that minimise the in-plane CTE mismatch on IMC growth facets, which are measured with electron backscatter diffraction (EBSD) in solder joints on Cu and Ni substrates. The CTE mismatch in fully-intermetallic joints is discussed, and the relationship between the directional CTE of monoclinic and hexagonal polymorphs of Cu 6 Sn 5 is explored. [ABSTRACT FROM AUTHOR]

Isothermal oxidation behavior of NbSi 2 coating grown on Nb substrate was investigated in air at 1000–1450 °C. Oxidation rate of NbSi 2 coating increased with temperature at 1000–1300 °C but opposite trend was observed at 1300–1450 °C. Maximum oxidation rate was obtained at 1300 °C due to the highest porosity of oxide scale. Lowest oxidation rate was observed at 1450 °C due to formation of dense oxide scale by combined effect of volatilization of Nb oxide phase, viscous flow and densification of c-SiO 2 . Oxidation resistance of NbSi 2 coating at these temperatures was governed by some inter-related factors. [ABSTRACT FROM AUTHOR]

The structural, magnetic and magnetoelastic properties of Tb x Ho 1−x Fe 1.9 Mn 0.1 (0.08 ≤ x ≤ 0.16) alloys have been investigated by means of X-ray diffraction (XRD), Mössbauer spectra, a vibrating sample magnetometer and a standard strain technique. The easy magnetization direction (EMD) at room temperature rotates continuously from the 〈100〉 axis for x = 0.10 to 〈111〉 for x = 0.14 through an intermediate direction around x = 0.12, subjected to the anisotropy compensation between Tb 3+ and Ho 3+ ions. The magnetocrystalline-anisotropy compensation can be obtained by performing XRD on magnetic-field aligned powders and by evaluating the EMD, magnetization process and magnetostriction. The compensation point achieved is around x = 0.12, shifting to the Ho-rich side at room temperature compared with the Mn-free system. Mn causes opposite contributions to the resultant anisotropy of the alloys as compared to Ho. A minimum in anisotropy is obtained for the Tb 0.12 Ho 0.88 Fe 1.9 Mn 0.1 compound, which has a high low-field magnetostriction (λ a ∼ 340 ppm @ 2 kOe). [ABSTRACT FROM AUTHOR]

The heat capacity of three Fe-rich bcc-based Fe-Al alloys (35, 40 and 45 at.% Al) and of the three Al-rich intermetallics ζ (FeAl 2 ), η (Fe 2 Al 5 ) and θ (Fe 4 Al 13 ) were measured by DSC between 120 K and their respective melting points. For the Fe-rich bcc-based alloys, the heat capacity was measured in the temperature range of the A2/B2 transition which reaches a maximum value of 54.7 and 86.3 J / K ⋅ mol for the samples with compositions of 35 and 40 at.% Al close to the order/disorder transition temperature of 1456 and 1555 K, respectively. The Debye temperature and the standard entropy values of the Al-rich intermetallic phases ζ ( Θ D = 455 K , S 298.15 = 24.45 J / K ⋅ mol ), η ( Θ D = 484 K , S 298.15 = 23.00 J / K ⋅ mol ) and θ ( Θ D = 469 K , S 298.15 = 23.65 J / K ⋅ mol ) were estimated based on low temperature c p values. All three intermetallics and the 45 at.% Al sample show a non-linear increase in c p by approaching the melting point which probably originates from the creation of thermal vacancies in the respective intermetallic phase. The enthalpy of formation of vacancies within the three phases ζ ( H f = 156 ± 4 kJ/mol ), η ( H f = 181 ± 3 kJ/mol ) and θ ( H f = 95 ± 2 kJ/mol ) was estimated based on the results of the high temperature c p measurements. [ABSTRACT FROM AUTHOR]

Time-differential perturbed angular correlation (TDPAC) measurements have been carried out in stoichiometric ZrNi 3 and HfNi 3 intermetallic compounds using 181 Ta probe in the temperature range 77–1073 K considering the immense technological applications of Zr-Ni and Hf-Ni intermetallic compounds. In ZrNi 3 , four components due to the production of Zr 2 Ni 7 , Zr 8 Ni 21 , Zr 7 Ni 10 and ZrNi 3 have been found at room temperature. The HfNi 3 sample produces five electric quadrupole interaction frequencies at room temperature. The phase HfNi 3 is strongly produced in stoichiometric sample of HfNi 3 where two non-equivalent Hf sites are found to be present. Besides this phase, two other phases due to Hf 2 Ni 7 and Hf 8 Ni 21 have been found but, we do not observe any phase due to Hf 7 Ni 10 . X-ray diffraction, TEM/energy dispersive X-ray spectroscopy (EDX) and TEM-selected area electron diffraction (SAED) measurements were used to further characterize the investigated materials and it was found that these results agree with the TDPAC results. In order to confirm findings from TDPAC measurements, density functional theory (DFT) based calculations of electric field gradients (EFG) and asymmetry parameters at the sites of 181 Ta probe nucleus were performed. Our calculated results are found to be in excellent agreement with the experimental results. [ABSTRACT FROM AUTHOR]