Search

Using cold isostatic pressing and atmospheric pressure sintering, Ti-18Al-28Nb-xSn alloys were synthesized by incorporating 0.5 at.%, 1 at.%, 2 at.%, and 4 at.% Sn powder into Ti, Al, and Nb powders. This study investigated the effects of Sn concentration on the microstructure and mechanical properties of Ti2AlNb-based alloys, with a particular focus on the underlying strengthening mechanisms. X-ray diffraction (XRD) analysis identified α2, O, and B2 as the primary phases in the alloy and demonstrated that Sn addition significantly influenced the proportions of these phases, thus impacting the overall mechanical performance of Ti2AlNb-based alloys. The optimal combination of elasticity, strength, and plasticity was achieved at a Sn concentration of 1 at.%; at this time, the elastic modulus of the alloy was 26.8 GPa, with a compressive strength of up to 1352 MPa and a fracture strain of 42.8%. However, further increases in Sn content beyond this level led to reductions in both strength and plasticity. At Sn concentrations above 2 at.%, increased porosity and the formation of micropores were observed, facilitating microcrack aggregation and fracture, which ultimately compromised the alloy's mechanical integrity. By exploring the intrinsic strengthening mechanisms, this study tries to understand the influence of Sn on the strengthening effects and to optimize the content range of Sn addition to ensure the best strengthening effect and good density are shown in high-Nb-content TiAl alloy, providing a reference for future research in this field. [ABSTRACT FROM AUTHOR]

In this paper, the combined effect of Sn addition and solution treatment temperature on natural aging (NA) hardness behavior and microstructure of Al-0.4Mg-1.0Si alloy were investigated by hardness test, scanning electron microscope (SEM) and scanning transmission electron microscope (STEM). The evolutions of clusters characterized by three-dimensional atom probe (3DAP) during initials stages of NA are also investigated based on the slow in formation of clusters due to Sn addition. The results shown that a Sn-rich particles with round shape retained in Al matrix after quenching treatment when the added Sn content exceeds it limit solubility, which will reduce the Mg content of the designed alloy. The suppression of NA can be enhanced with the increase in the adding Sn content and solution treatment temperature, which is strongly related to the delay of the segregation of Mg and Si to form clusters due to more trapping vacancies by Sn atoms. The addition of Sn also revealed that the segregation of Si during NA is earlier than that of Mg atoms. The Si-rich clusters are formed preferentially during initial stage of NA, and Mg–Si co-clusters are formed after long period of NA. The Mg/Si ratio and average size of Sn-containing clusters in the 0.04%Sn and 0.1%Sn alloy are obviously higher than that of Sn-free clusters regardless of the 1 day NA or 14 days NA as more Mg atoms are dragged into Sn-containing clusters due to strong interaction between Sn and Mg atoms.

The effect of Sn addition on age-hardening and precipitation behavior of Al-Mg-Si alloy with different Mg/Si ratios was investigated by using the hardness test and TEM characterization. The results indicate that the addition of Sn increases the number density of precipitates of the peak-aged alloy with low Mg/Si ratio, but decreases the precipitation rate of β″. Hence, the hardening rate and peak aging hardness of alloy with low Mg/Si ratio decrease by the addition of Sn. During over-aging, the high precipitate densities of Sn-added alloy improve the over aging hardness of the alloy with low Mg/Si ratio. For alloy with high Mg/Si ratio, the addition of Sn not only increases the precipitate density, but also enhances the precipitation rates of β″. Therefore, the hardening rate and peak-aging hardness of alloy with high Mg/Si ratio increase by the addition of Sn.

The effects of Cu and Sn additions on the precipitation hardening of Al-Mg-Si alloys were systematically studied by performance testing and microscopic characterisation. Sn addition can retard the onset of natural aging (NA), while after long-term NA, the NA hardening is enhanced. Although Cu and Sn can promote the NA hardening, the Cu and Sn combination addition results in NA hardness lower than the individual Cu addition. Compared with Sn, Cu addition is more efficient in promoting the artificial aging hardening of these alloys. Both of the Sn and Cu atoms can incorporate in the interior of the β′′ phase and produce disordered structure. The results are expected to provide new insight for designing new aluminium alloys for automotive application. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The combined effect of Sn and pre-aging on hardening and precipitation behavior of Al-1.0Mg-0.6Si(-0.3Cu) alloy was investigated by using hardness measurement, tensile test, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results indicated that the natural aging (NA) hardening of Al-1.0Mg-0.6Si (−0.3Cu) alloy was suppressed by pre-aging treatment, and the suppression of NA can be enhanced by the addition of Cu. However, the suppression of NA time of Al-1.0Mg-0.6Si and Al-1.0Mg-0.6Si-0.3Cu alloy, i.e., without obvious hardness increase after pre-aging treatment, is reduced to 5 and 7 days by the addition of Sn, which is not conducive to the suppression of NA. For subsequent artificial aging (AA) of the Al-1.0Mg-0.6Si (−0.3Cu) alloys, the AA precipitation of Al-1.0Mg-0.6Si alloy with pre-aging treatment is accelerated by the addition of Sn or Cu, particularly by adding both Sn and Cu, resulting in the increase in the bake hardening response. The effect of the evolution of clusters after pre-aging on underling mechanisms of NA and its AA were also discussed.

The effect of Sn content on the microstructure evolution of the as-cast, as-extruded and as-aged Mg-8Zn-2Y-xSn alloys were systematically investigated. The results show that addition of Sn not only refines the grains but also promotes the precipitation of quasicrystal I-phase and the formation of Sn3Y5. The phase transformations during solidification were also studied in detail. After extrusion, the broken second phase particles (I-phase) are more uniformly and densely distributed in the matrix with Sn addition. Moreover, ultra-fine dynamically recrystallized grains are obtained in extruded Mg-8Zn-2Y-0.5Sn alloy. In addition, high density nano-scale precipitates are uniformly dispersed by aging, and these precipitates are identified to be Mg-Zn particles, I phase and mixture of the β 1 ′ Mg-Zn precipitates and I-phase. [ABSTRACT FROM AUTHOR]

Effects of Sn and Gd additions on the (β1 + β3) field in the Cu-11%Al-10%Mn alloy were studied by in situ X-ray diffraction, differential scanning calorimetry, non-isothermal kinetics, and magnetization measurements as a function of the temperature. The microstructures were investigated using optical microscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The results showed that the β 3 Cu 2 AlMn + β 1 Cu 3 Al → β 3 Cu 2 AlMn reaction is strongly dependent on the heating and cooling rates. The Sn addition to the Cu-11%Al-10%Mn alloy stabilizes the ferromagnetic β3 phase. In the Sn-containing alloy, the miscibility gap transition is followed by the martensitic transformation at about 560 K. Both Sn and Gd additions have extended the stability field of the ferromagnetic β3 phase. Nonetheless, the formation of Cu5Gd precipitates slows the miscibility gap transition on heating, which may be associated with the reduction of the ferromagnetic phase amount at room temperature in the Cu11%Al10%Mn3%Gd alloy. [ABSTRACT FROM AUTHOR]

Based on the "Clyne-Davies" hot tearing prediction model, the effect of Sn addition on the hot tearing susceptibility (HTS) of Mg-4Zn-xSn-1Ca (x=0, 0.5, 1.0, 2.0 wt%) alloy was studied using "T-shaped" hot tearing mold at a pouring temperature of 700 °C and a mold temperature of 270 °C. The dendrite coherency temperature was obtained by means of differential thermal analysis. The Phase transformation, microstructure, and morphology of the crack zone of Mg-4Zn-xSn-0.6Zr alloys were investigated via scanning electron microscopy and optical microscopy. Mg-4Zn-xSn-1Ca alloys were found to be composed of α-Mg, Ca2Mg6Zn3, and CaMgSn phases. The appropriate Sn addition was shown to be an effective way for refining grains, decreasing the dendrite coherency temperature and increasing the liquid film thickness, which could reduce the HTS of the Mg-4Zn-xSn-0.6Zr alloys. However, excessive Sn content made the acicular CaMgSn phases gather together to form a network structure, which affected feeding of the residual liquid phase and increased the alloy's HTS. In studied alloys, the HTS followed a sequence of CSC (Mg-4Zn-1Ca)>CSC (Mg-4Zn-0.5Sn-1Ca)> CSC (Mg-4Zn-2Sn-1Ca)> CSC (Mg-4Zn-1Sn-1Ca). [ABSTRACT FROM AUTHOR]

The effect of Sn on the hot deformation behavior of Mg–Ca–Mn alloy at the temperature of 30~450 °C and strain rate of 0.001 to 5 s−1 was studied. The results indicated that the addition of Sn increased the low-temperature and low-strain processing region, which was mainly due to the large amount of CaMgSn second phase promoting the dynamic recrystallization at low temperatures and low strain rates. In addition, the expanded region has been successfully applied to the rolling deformation process. The maximum single-pass rolling deformation of the alloy containing Sn increased from 30 to 40%. This is mainly attributed to CaMgSn precipitates which decreased the dynamic recrystallization temperature. Therefore, the dislocations generated in the rolling deformation were effectively consumed, with consequent increase in the single-pass deformation. [ABSTRACT FROM AUTHOR]

Herein, the effect of SnCl4 addition on the catalytic performance of Pd–Cu/attapulgite (Pd–Cu/APT) synthesized by a deposition–precipitation method has been investigated. Compared with Pd–Cu/APT, the suitable addition of Sn has a conspicuous facilitation on the catalytic performance of Pd–Cu–Sn/APT for CO oxidation. The characterization results reveal that the incorporation of Sn gives rise to the formation of SnO2, which conduces to produce the more Cu2Cl(OH)3 active phases and Cu+ species in Pd–Cu–Sn/APT and establish a mutual interaction between Sn and Pd, Cu species. Accordingly, the Pd0 species generated during CO oxidation over Pd–Cu–Sn/APT can be more easily oxidized than those over Pd–Cu/APT. Additionally, the generation of SnO2 is prone to suppress the adsorption of water vapor on the catalyst surface, hence augmenting the water resistance of Pd–Cu–Sn/APT. Therefore, Sn-modified Pd–Cu/APT catalyst exhibits the more excellent catalytic performance for CO oxidation at room temperature under moisture-rich conditions. [ABSTRACT FROM AUTHOR]

Sintering of active Ni sites and deposition of coke remain challenging issues for catalytic dry reforming of methane. Herein, Ni supported on the Sn‐incorporated MCM‐41 catalysts were synthesized and tested for DRM process. The structural and physicochemical properties of fresh and spent samples were studied by N2 adsorption‐desorption, XRD, H2‐TPR, XPS, TEM, STEM‐EDS, Raman, and TGA techniques. It was revealed that Sn addition improved the dispersion and decreased the size of active Ni nanoparticles by tuning the charger transfer between Ni and Sn. The formation of Ni−SnOx interface provides more possibilities to activate CO2. The best results were obtained by 2Ni/Sn−MCM‐41 sample with the Ni/Sn mole ratio of 2 : 1, contributing CH4 conversion of 95% and CO2 conversion of 94% at 800 °C. Moreover, the presence of Sn increased the resistance to sintering of Ni‐based catalysts during the severe conditions, thereby the Ni nanoparticle size only appeared a slight growth after 32 h TOS. Combined with the characterization of the spent 2Ni/Sn−MCM‐41 sample, it was revealed that the coke deposition of the deactivated catalyst was dominated by amorphous carbon, which could be responsible for the desirable regeneration ability of the catalyst. [ABSTRACT FROM AUTHOR]

The combined effect of adding Sn and natural aging (NA) time on the precipitation and age-hardening rate of the Al-0.4Mg-1.0Si alloy was investigated by a hardness test, electrical resistivity test, differential scanning calorimetry (DSC) analysis, 3-D atom probe (3DAP) analysis, and transmission electron microscopy (TEM). The results showed that the NA of the Al-0.4 Mg-1.0Si alloy was suppressed by adding Sn. This suppression was ascribed to the suppression of the formation of clusters. The short NA time (less than 5 days) had a positive effect on the subsequent artificial aging (AA) in the Sn-added alloys, i.e., a fast AA-hardening rate was achieved. The positive effect of the NA on the AA in the Sn-added alloys increased as the amount of Sn increased, but decreased as the NA time increased. The AA was negatively affected by the NA when the NA time was increased to 14 days. The accelerated AA precipitation of the Sn-added alloys after a short NA time was responsible for the fast AA-hardening rate. This accelerated precipitation was related to the increased amount of retained quenched-in vacancies according to their NA resistivity curves and similarity of the chemical composition between the Sn-containing clusters and β'' phases.

In the present study, the Cu-24Pb-xSn (wt.%) alloys with Pb-rich secondary phase particles (SPPs) in different morphology were prepared by intermediate frequency induction heating technology. The experimental results show that the SPPs transform from network to rod-like morphology with Sn content increasing from 0 wt% to 6 wt%. The relevant function mechanism of Sn addition was revealed through synchrotron X-ray radiography and thermodynamic analysis. It is indicated from the thermodynamic calculation that Sn addition can weaken the demixing tendency in Cu-Pb system. This can also lead to intensity drop of the monotectic reaction which was characterized by differential scanning calorimetry (DSC). Simultaneously, a triple-phase-coexistence (TRPC) region is introduced with Sn addition during solidification, which contains a Cu-rich liquid (L 1), a Pb-rich liquid (L 2) and a solid α-Cu (S). Benefitted from the mobility of these two immiscible liquids, L 2 tends to show regular rod-like morphology and finally transform to rod-like SPPs, which is similar to some immiscible alloys containing an immiscibility gap, such as Al-Pb, Al-Bi and Ti-Ag alloys. The width of TRPC region in the pseudobinary phase diagram of Cu-Pb-Sn alloy increases with increasing Sn content. This is attributed to the fact that increasing Sn content can lead to the drop of interfacial tension between L 1 and L 2. Simultaneously, the interfacial tension drop will decrease the Marangoni migration velocity of the SPPs, and the Marangoni migration serves as the main driven force of SPPs' collision and coagulation in this case. Therefore, Sn addition is helpful to obtain fine and dispersed SPPs in this case. This work possesses guiding significance to the composition design and production of relevant hypomonotectic alloy with homogeneous and refined microstructure. • SPPs transform from network to rod-like morphology in Cu-Pb-Sn alloy with increasing Sn content. • Effect of Sn addition is revealed through synchrotron radiation and thermodynamic analysis. • Sn addition weakens the demixing tendency in binary Cu-Pb system and introduces a TRPC region during Solidification. [ABSTRACT FROM AUTHOR]

Abstract Tailoring the properties of an engineering material with low coefficient of friction (COF) and high wear resistance has been a long goal in the tribological research. It is particularly true for the bulk metallic glass composites (BMGCs), which are promising for a large range of advanced applications. Although the materials design and mechanical properties have been extensively investigated, knowledge of their tribological behaviors is still lacking. Ball-on-block wear tests were thus conducted to investigate the effect of Sn addition on the tribological behaviors of Ti 45 Zr 25 Nb 6 Cu 5 Be 17 BMGCs under different normal loads. Nano-indentation and nano-scratch tests were carried out to study the phase-specific wear properties of the crystalline dendrite and amorphous matrix in BMGCs respectively. Preferred wear and delamination in the dendrite phase as a result of the plastic mismatch between the two constituent phases is responsible for the abrasive wear in the Ti 47 Zr 25 Nb 6 Cu 5 Be 17 and Ti 46 Zr 25 Nb 6 Cu 5 Be 17 Sn 1 BMGCs. While, mechanically driven tribolayer during sliding enables oxidative wear and improved tribological properties in the Ti 45 Zr 25 Nb 6 Cu 5 Be 17 Sn 2 BMGC. Based on the synergistic mechanical and chemical effects, the underlying relationship between the intrinsic dendrite properties and the wear behaviors of BMGC was revealed. Graphical abstract Image 1 Highlights • BMGC with 2 at.% Sn exhibit a much higher wear resistance. • The dendrite phase shows distinct strain hardening and oxidation behavior during the wear process. • Sn element was found to affect the wear mechanism transformation from abrasive wear to oxidative wear. [ABSTRACT FROM AUTHOR]

Age-hardening aluminum alloys generally exhibit poor thermal stability, making them unsuitable for prolonged use at temperatures around the aging range. This study investigated the effect of 0.08 wt% Cu and 0.05 wt% Sn on the thermal stability of peak-aging Al–0.9Mg–1.1Si (wt.%) alloy. After an exposure of 150 °C for 1000 h, the combined effects of Cu and Sn result in a higher yield strength (∼322 MPa) than that of the Cu/Sn-free alloy (∼311 MPa). This improvement is mainly attributed to the Sn-induced fine precipitate morphology. Specifically, precipitates with higher aspect ratios exhibit rapid coarsening rates, significantly promoting the response of experimental alloys to thermal exposure. In contrast, precipitates with lower aspect ratios coarsen at a slower rate and maintain a higher level of strengthening during thermal exposure. Furthermore, Sn atoms may also contribute to the formation of the thermostable Cu-containing phases (L phase). On the one hand, the Sn-induced higher precipitate density will increase the amount of L phase. On the other hand, the special Sn-containing sub-units may serve as heterogeneous nucleation sites to promote the formation of L phase. In summary, the combined effects of Cu and Sn enhance the thermal stability of the experimental alloys near the aging temperature range. The present study provides a straightforward and feasible approach to enhancing the thermal stability of Al–Mg–Si alloys. [ABSTRACT FROM AUTHOR]

The formation of the metastable phases in aluminium alloys is closely linked with the excess vacancies. Traces of tin added to an Al-Ag alloy exert an influence on the precipitation kinetics. In the quenched Al-Ag alloys, the precipitation is controlled by the diffusion of solute atoms which require the presence of free vacancies. Due to their high binding energy with vacancies, tin atoms modify the nucleation and growth characteristics of the phases which form during precipitation. Tin atoms retard the precipitation of the Guinier-Preston zones at 90, 125 and 150 °C, suppresses it at 170 and 200 °C and, at all temperatures, stimulate the precipitation of the metastable γ’ phase.

The present work investigated systematically the glass forming ability, the mechanical properties and the shear deformation of the TiZrHfCuBe high entropy bulk metallic glass (HE-BMG) with minor Sn addition. The results revealed that the glass forming ability and the thermal stability are enhanced by minor Sn addition but within a rather limited composition range. A nanoindentation study of the mechanical response in the (TiZrHfCuBe) 1- x Sn x ( x  = 0, 1, 2 and 3 at. %) HE-BMGs showed that the structural heterogeneity caused by Sn addition resulted in higher hardness, larger number of shear bands and smaller size of shear transformation zone, ascribing to the positive enthalpy of mixing between the Sn and Cu/Be elements. A statistical analysis of the serrated flow revealed that the chemical heterogeneities promote a relatively large population of shear deformation units and lead to multiple nucleation of shear bands. The present work might has implications in establishing the link between minor element addition and structure heterogeneity, which is of critical importance for understanding of shear banding behaviors in BMGs. [ABSTRACT FROM AUTHOR]

The effect of boron carbide (B4C) particles and Sn on the microstructure and mechanical properties of Mg94Y2.5Zn2.5Mn1 alloy is mainly studied in this work. The results show that separated addition of B4C and Sn could not achieve very good results. The separated addition of Sn significantly promotes the formation of LPSO phase, but it cannot change the growth pattern of LPSO phase and W phase. Adding B4C changes the growth pattern of LPSO phase, but cannot effectively promote the formation of LPSO phase. The addition of B4C and Sn in combination achieves the growth pattern transformation of α‐Mg from irregular dendrite to equiaxed dendrite and refines the grain size, which makes LPSO phase and W phase no longer grow by coupled growth. When 0.02 wt% B4C and 0.35 wt% Sn is added, the Mg94Y2.5Zn2.5Mn1 alloy's growth pattern is changed and grains are refined, and thus exhibit superior mechanical properties. (Ultimate tensile strength of 255 MPa and elongation of 8.8%). [ABSTRACT FROM AUTHOR]

In this work, the high-temperature compression behavior of high Nb-containing TiAl–Sn alloys was investigated at deformed temperatures of 700 °C–1000 °C and strain rates of 0.002 s−1–0.2 s−1. The true stress-strain curves, microstructures, and constitutive equations of TiAl-xSn (x = 0, 0.5, 1, 1.5) alloys under different deformation conditions were systematically compared. Sn addition can increase the flow stress of TiAl alloys at the same deformation temperature, which is caused by the solid solution strengthening effect. At 800 °C/0.002 s−1, the peak flow stress of TiAl–1Sn alloy increases by 180 MPa compared with TiAl–0Sn alloy of 600 MPa. Below the peak stress, the flow stress increases with the increase of strain. Above the peak stress, the flow stress first decreases and then gradually trends to a steady state as the increase of deformation. Furthermore, the Sn addition decreases the brittle-ductile transition temperature of TiAl alloys. The TiAl-xSn (x = 0.5, 1, 1.5) alloys displays obvious flow softening behavior at 700 °C while TiAl–0Sn alloy fractures before reaching the target deformation. The relationship between of the flow stress, strain rate, and deformation temperature for TiAl–0Sn and TiAl–1Sn alloys is suitable for the hyperbolic sinusoidal equation. The dominant softening mechanism of hot deformation for TiAl-xSn (x = 0, 1) alloys is dynamic recrystallization (DRX). The activation energies Q of hot deformation for TiAl–0Sn and TiAl–1Sn alloys are 311 kJ mol−1 and 429 kJ mol−1 at condition of 700–1000 °C/0.002–0.2 s−1, indicating that the TiAl–1Sn alloy exhibits a better stability under the same application condition. • Sn Addition increases the flow stress of TiAl alloys at the same deformation temperature. • Sn Addition decreases the brittle-ductile transition temperature of TiAl alloys. • TiAl–1Sn alloy exhibits a better stability under the same hot deformation conditions. [ABSTRACT FROM AUTHOR]

High-strength hot press forming (HPF) steel sheets are coated mostly by Al-Si to prevent the decarburization or oxidation of sheet surfaces, but become vulnerable to hydrogen embrittlement (HE) as H atoms supplied from moisture in a furnace penetrate through the molten coating into the steel substrate during the HPF process. In this study, 0.1-wt% of Sn was added to a 1.5-GPa-grade reference HPF steel (referred to as 0.1Sn and Ref steels), and their coating microstructures including Sn-enriched zone and Kirkendall and surface voids were examined after laboratory-scale HPF simulation tests. The content of diffusible H atoms immediately after the HPF simulation at 900 °C was 0.111 wt.ppm in the Ref sheet, decreased slowly as the elapsed time increased, and remained to be 0.030 wt.ppm even after 17 days. In the 0.1Sn sheet, it was about half of that of the Ref sheet (0.061 wt.ppm), and decreased rapidly to nil after 3 days. These results indicated that the 0.1Sn steel showed excellent H-intrusion and emission behavior, which would favorably work for better resistance to HE, by optimally controlling the multi-mechanisms of enrichment of Sn solutes and population of coating voids. The presence of Sn-enriched zone and voids played an important role in blocking the H intrusion to the substrate and in accelerating the H emission to the coating surface, respectively. • Sn-enriched zone blocks the H intrusion to the substrate. • Voids accelerate the H emission to the coating surface. • If less H comes in and goes out quickly, it is resistant to hydrogen embrittlement. [ABSTRACT FROM AUTHOR]

The effects of Sn addition (0, 0.5, 1.0, 2.0 and 3 wt%) on microstructure of Mg-4Zn-1.5Al alloy in cast and extruded states were investigated, and the mechanical properties of as-extruded Mg-4Zn-1.5Al-xSn studied. The experimental results showed that the as-cast Mg-4Zn-1.5Al alloy was composed of two phases α-Mg and Mg 32 (Al, Zn) 49 , while Sn-containing alloys consisted of α-Mg, Mg 32 (Al, Zn) 49 and Mg 2 Sn phases, and Mg 32 (Al, Zn) 49 was not detected after extruding due to that the most of them dissolved into the matrix during the homogenized treatment. The addition of Sn refined the grains of as-cast and as-extruded Mg-Zn-Al alloys obviously. It was noted that the basal texture intensity reduced with increasing Sn content significantly in as-extruded Mg-Zn-Al alloys. The tensile tests results indicated that Sn addition improve the tensile strength of the extruded alloys, while it had a harmful effect on the ductility. When the addition of Sn was 2 wt%, the ultimate tensile strength (UTS), yield strength (YS) and elongation (ε f ) of the alloy were 280 MPa, 147 MPa and 17.4%, respectively. [ABSTRACT FROM AUTHOR]

Excess impurity Fe will form various intermetallic compounds in Al-based alloys, such as α-Al 8 Fe 2 Si and β-Al 5 FeSi, which greatly reduce the elongation of alloys. Therefore, Fe removal is a promising approach for high performance Al-based alloy. In this paper, we propose an effective method for the Fe removal from Al-7Si alloys by adding Sn. Based on the thermodynamic calculations, the element Sn was selected for Fe removal. The microstructure of Fe-rich compounds and Fe content in alloy were compared by optical microscope (OM), scanning electron microscopy (SEM) and inductively coupled plasma generation spectrometer (ICP). It was observed that the reduction of Fe content in Sn can reach 33.8%, comparable to the level of adding B. More Fe-rich compounds deposited at the bottom after addition of Sn. However, the phase type and morphology of Fe-rich compound were unchanged. The β-Sn attached to the β-Al 9 Fe 2 Si 2 which was determined by transmission electron microscopy (TEM), and a coherent interface between β-Sn and β-Al 9 Fe 2 Si 2 phase was observed with the orientation of (0 0 1)[1 1 0] β-Sn ∥(2 2 0)[0 0 1] β-Al9Fe2Si2. It deduced that the attached β-Sn with larger density than alloy would lead to more deposition of β-Al 9 Fe 2 Si 2. This study provides an insight into the preparation of high-performance Al-Si alloy by removing Fe from secondary Al alloy with Sn addition. [Display omitted] • Sn is selected for iron removal based on the thermodynamic calculations. • The iron removal rate of Al-7Si-1Fe can reach 33.8% by adding Sn. • The β-Sn will attach to the surface of β-Al 9 Fe 2 Si 2 phase and settle it. [ABSTRACT FROM AUTHOR]

The influence of small Sn addition on the mechanical properties and microstructure of an Al-Cu-Mg-Ag alloy is systematically investigated in this work. The age-hardening level of the material at 180 ℃, as well as the strength properties during exposing at 200 ℃, is found to decrease with small Sn addition. With Sn, the morphology of the tensile fracture surface gradually evolves from a transgranular mode to an intergranular one during the prolonged exposing at 200 ℃. Quantitative transmission electron microscopy (TEM) analysis proposes the negative role of Sn on the dense precipitation of Ω phase by accelerating the θ' formation, thereby leading to a loss of strength properties and the lower thermal stability of Sn-added alloy. This detrimental effect by Sn, as revealed by atom probe tomography (APT), is primarily ascribed to the suppressed Mg-Ag co-clustering, which reduces the nucleation rate of Ω phase. Our calculation also indicates that a reduction of the cluster hardening by Sn is mainly responsible for the observed loss in the strength of underaged alloy. The contributions of modulus hardening and order hardening to the cluster hardening are also quantified for each cluster. A similar recrystallized grain size in Sn-free and Sn-added alloys eliminates the grain refinement effect by Sn. • Small Sn addition reduces the age-hardening level and strength properties of Al-Cu-Mg-Ag alloy. • The Ω precipitation is restricted by Sn addition due to the limited Mg-Ag co-clustering. • The effect of Sn on the individual contribution of various clusters to strengthening is quantified based on APT data. • The cluster hardening is found to be significantly reduced by Sn addition. • Sn has no obvious influence on the grain structure of Al-Cu-Mg-Ag alloy. [ABSTRACT FROM AUTHOR]

Ni/SiO2 catalysts with large surface area Ni particles exhibit high hydrogenolysis activity, leading to the formation of large amounts of methane and coke. To destroy the active sites for hydrogenolysis, namely the aggregated Ni ensembles, Sn species were introduced into the Ni/SiO2 catalyst. As expected, isobutene selectivity was significantly increased to 90.2 %. The promoting role of Sn on the dehydrogenation performance could be interpreted as both a geometric and electronic effect. On one hand, Sn addition efficiently dispersed aggregated Ni particles and reduced Ni particle size from 77 to 16 nm, weakening the ability of Ni for C−C bond rupture. On the other hand, additional electrons provided by Sn led to a high electronic density of Ni, facilitating the desorption of isobutene from the catalyst and suppressing secondary reactions. Consequently, coke formation was effectively inhibited over the NiSn/SiO2 catalyst, further guaranteeing a good stability and prolonged cycle time. [ABSTRACT FROM AUTHOR]

An experimental investigation is performed into the mechanical behaviour, fracture properties and glass forming ability (GFA) of Ti-based bulk metallic glass (BMG) with Tin (Sn) addition. The experimental results show that the flow stress and strain rate sensitivity of the considered Ti 44 Cu 40 Ni 16 − x Sn x ( x = 0, 1, 2 at.%) alloy system increase with increasing strain and strain rate. The fracture surfaces of the specimens are observed by using Scanning electron microscopy. Moreover, the fracture surfaces have a vein-like characteristic whose density decreases with an increasing strain rate and Sn addition. Finally, 1% Sn addition inhibits the precipitation of crystalline CuTi 2 phase and improves both the ductility and the GFA of the alloy system. [ABSTRACT FROM AUTHOR]

The effect of adding Sn to an extruded Mg–8Al–2Zn (AZ82 alloy) was investigated by analyzing its microstructural characteristics before and after extrusion, and by conducting tensile and compressive tests with 2, 4, and 6 wt% Sn addition. This revealed that although second phases formed during solidification are nearly fully dissolved by homogenization treatment in AZ82 alloy with 2 wt% Sn, numerous Mg 2 Sn particles remain in AZ82 alloys with 4 and 6 wt% Sn due to this concentration being over the solubility limit. All of the extruded alloys were found to have a fully recrystallized structure, yet the addition of 6 wt% Sn created a considerable quantity of large, banded Mg 2 Sn particles oriented along the extrusion direction. The tensile and compressive yield strength gradually increased with Sn content mainly due to a decrease in the size of recrystallized grains and an increased amount of fine Mg 2 Sn precipitates, though this came at the expense of a decrease in elongation. It was also found that the ultimate tensile strength improves with Sn addition of up to 4 wt%, but deteriorates beyond that point due to premature fracture caused by crack initiation at large particles. [ABSTRACT FROM AUTHOR]

The present work investigated the effect of Sn on the microstructure, hardness, and tribological behaviors of CoCrFeNi high entropy alloys fabricated via vacuum arc melting. The results showed that Sn addition in CoCrFeNi alloys led to a distinct structure change from single FCC to dendritic microstructure in which Ni 3 Sn 2 phase was distributed between the FCC dendrites. With the increase in Sn content, the volume fraction of Ni 3 Sn 2 phase increased and thus brought about the improved hardness due to the second phase strengthening. The friction and wear test indicated that the best tribological performance was achieved by Sn 1 alloy under a load of 2 N (the friction coefficient and wear rate were as low as 0.21 and 2.7 × 10−5 mm3/N∙m, respectively), which was attributed to the competitive effect between the applied load and Sn content. Moreover, the wear mechanisms of CoCrFeNiSn x alloys during sliding were carefully discussed. • Sn addition changed main wear mechanism from abrasive wear to oxidative wear. • CoCrFeNiSn 1 alloy exhibited the best tribological performance during dry sliding. • It was related to the improved hardness and the formation of SnO 2. [ABSTRACT FROM AUTHOR]

Inheriting the advantages of bulk metallic glasses (BMGs) and high entropy alloys (HEAs), high entropy bulk metallic glasses (HE-BMGs) have sparked great interest in recent years. In this work, the evolutions of structural heterogeneity, thermal stability and mechanical property of the TiZrHfCuBe HE-BMG with minor Sn addition were characterized, and the corresponding tribological properties under different normal loads and frequencies were investigated. The results showed that minor Sn addition can significantly enhance wear resistance of the HE-BMG by improving its structural heterogeneity and mechanical properties in a rather limited composition range. When excessive Sn is added, plentiful crystal particles are precipitated in the amorphous matrix, and the wear mechanism of the HE-BMG changes from slight abrasive and oxidation wear to severe fatigue and oxidation wear, leading to dramatically declined wear resistance. These findings would provide guidance for the development of advanced HE-BMGs with unique properties. • A rather limited Sn addition could enhance mechanical properties and wear resistances of (TiZrHfCuBe) 1- x Sn x HE-BMGs. • Declined wear resistance of the (TiZrHfCuBe) 0.97 Sn 0.03 was caused by the excessive Sn addition. • The wear mechanisms of (TiZrHfCuBe) 1- x Sn x HE-BMGs change from abrasive and oxidation wear to fatigue and oxidation wear. [ABSTRACT FROM AUTHOR]

Highlights: [•] A systematic study on the effects of sintering temperature and Sn addition. [•] Field independence of Jc for the samples sintered at 850°C is optimal. [•] High transport Jc values have been achieved in all Sn-added tapes. [•] Sn addition involves in the Sr-122 phase formation and affects its composition. [•] Jc improvement is related to well connected grains, growth steps and dislocations. [ABSTRACT FROM AUTHOR]

Abstract: The effects of Sn addition on the microstructure and mechanical properties of as-cast, as rolled and subsequent isothermal annealed Mg–4Zn alloys are investigated. Tensile and Rockwell hardness tests are conducted to evaluate the mechanical properties of the as-cast alloys. Improvements of the mechanical properties in Sn-containing alloys are attributed to the increasing volume fraction of secondary phases and modifying the type of intermetallic phases. Additions of Sn increase the twinning density and modify the annealing texture in as-rolled Mg–4Zn alloys. In comparing rolled-annealed Mg–4Zn to Mg–4Zn–3Sn alloy, numerous small particles are dispersed in the matrix of rolled-annealed Mg–4Zn–3Sn alloy. The particles exhibit two different morphologies and sizes: nanosized Zn-rich particles and rectangular-shaped Mg2Sn particles with a size of about 175nm. The rolled-annealed Mg–4Zn–3Sn alloy exhibits high ultimate tensile strength, yield strength and elongation of 273MPa, 159MPa and 16.2%, respectively. The UTS and YS are about 16% and 53% higher than Sn-free alloy. [Copyright &y& Elsevier]

Highlights: [•] Mg–xLi–3Zn–1Sn–0.4Mn alloys were melted and extruded at 200°C. [•] Li addition resulted in the formation of MgLi2Sn intermetallic compound. [•] Li addition resulted in the development of the random texture. [•] By Li addition, the ductility was significantly increased. [•] Sn addition resulted in the improvement of strength. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the effect of Sn addition on the thermal and structural behaviour of (Cu60Zr25Ti15)100− x Sn x (x =0, 1, 2, 3 and 4) alloys. Expansion of the amorphous phase causing larger inter-atomic distances is observed with increasing Sn content. The glass transition temperature (T g) and the onset of the first crystallization temperature (T x) shifts to higher temperatures for alloys with increased Sn content. These, together with the increase in the activation energy of the 1st crystallization peak obtained from Kissinger analysis indicate the enhanced thermal stability of the alloys with increasing Sn content. Sn addition also widened super cooled liquid region of the alloys. TEM and XRD studies show nucleation of nano crystals associated with the first exothermic events. The size of the nano crystals increased from 6 to 20nm when the Sn content varied from 0 to 4at.%. A plausible explanation is invoked for the increase in the size of nano crystals with increase in Sn content. Irrespective of the Sn content all the alloys transform to Cu51Zr14 crystalline phase after the second exothermic peak. Glass transition temperature of the alloys varies with heating rate following Lasocka’s relationship; using the relationship, the theoretical limits of the low temperature range of the glass transformation region, i.e. for the heating rate β =1, of these alloys are also estimated. [Copyright &y& Elsevier]

Abstract: Lap joint of AZ31B Mg alloy to Q235 steel by hybrid laser-TIG welding was studied. Microstructures of Sn-free and Sn-added joint were investigated, and the intermediate phase of Sn-added joints was also inspected. In contrast with the Sn-free joints, intermetallic compound Mg2Sn with dendritic structure distributed in the grain boundaries of Mg alloy was identified; Gaps at the interfaces were vanished as the wettability of Mg alloy with the addition of Sn on steel was improved. Big particles in fusion zone became even smaller or disappeared in the Sn-added joints. [Copyright &y& Elsevier]

The effect of Sn on the hardening and corresponding precipitation behavior of as-quenched Al–0.4Mg–1.0Si alloy at different aging temperatures was investigated with hardness tests, differential scanning calorimetry analysis, and transmission electron microscopy. The hardness of the Sn-free alloy was higher than that of the Sn-added alloys during under-aging, but the tendency is reversed during over-aging. The effect of Sn on the hardening behavior of these alloys is not substantially affected by the aging temperature, i.e., the addition of Sn can improve resistance to over-aging softening at different aging temperatures. The reason for the resistance to over-aging softening by the addition of Sn is related to the increase in the number density of precipitates during under-aging and the decrease in precipitates size during over-aging. • The hardness of Sn-free alloy aged at different temperatures during under-aging and over-aging are higher and lower than that of the Sn-added alloys. • The advantage of the addition of Sn can improve the resistance to over-aging softening. • The higher hardening response of Sn-free alloy than that of Sn-added alloys during under-aging is attributed to large precipitate size and the fast precipitation of β". • The higher hardness of Sn-added than that of Sn-free alloys during over-aging is due to higher number density of precipitates. [ABSTRACT FROM AUTHOR]

The microstructure evolution, phase transitions, and corrosion behavior of the as-quenched Cu 77.45 Al 22.55 , Cu 67.83 Al 22.24 Mn 9.93 , and Cu 75.76 Al 22.82 Sn 1.41 alloys were analyzed using differential scanning calorimetry, optical and scanning electron microscopy, X-ray energy dispersive spectroscopy, and microhardness measurements. The phase quantifications in as-quenched alloys were obtained from X-ray diffraction using the Rietveld method. The corrosion behavior of the alloys was also studied using electrochemical impedance spectroscopy and potentiodynamic polarization. The analyses revealed both Sn and Mn stabilized the β phases in a wide temperature range. The martensitic transformation was shifted to a higher temperature interval due to the presence of Sn, while the manganese moved it to a lower temperature range, as compared with binary alloy. In addition, the Sn increased the effect of the Jerky step on the martensitic structure. The corrosion potential was reduced with Mn addition to the Cu–Al alloy. The Sn interfered with the corrosive behavior of the Cu 77.45 Al 22.55 alloy. [Display omitted] • The Sn and Mn additions to the as-quenched Cu 77.45 Al 22.55 alloy stabilize the β phases. • The Mn addition decreases the corrosion rate of the as-quenched CuAl alloy. • The Sn addition increases the corrosion rate of the as-quenched CuAl alloy. [ABSTRACT FROM AUTHOR]

Abstract: The influence of the addition of 0.5wt.% Sn to Al–7Si–0.3 Mg alloys (356 and A356) on their ageing behaviour and mechanical properties was evaluated. Adding Sn led to a reduction of the iron rich intermetallics volume fraction, and of hardness. During solution heat treatment, Mg went into the solid solution, and Sn particles grew by competitive growth, concentrating at phase boundaries and interfaces. During aging β″ and Si precipitated. In the alloys with Sn, the β″ precipitation was accelerated and its hardening effect was greater, whereas the Si precipitation did not changed significantly. The mechanical properties of the A356 alloy were compatible with the hardening achieved during the heat treatment and to the amount of defects (pores) present in the microstructure. The yield strength and elongation of the A356+0.5% Sn alloy decreased after solution heat treatment and with increasing ageing temperature. These detrimental effects were minimized by treating this alloy in the T5 condition at 150°C. [Copyright &y& Elsevier]

Abstract: The effects of addition of Sn on the microstructure and mechanical properties of rolled Mg–MM alloy sheets have been investigated. The secondary solidification phase in Mg–MM alloy changes dramatically with addition of Sn forming small size rod-shaped phase. Although the strength of alloy is decreased with addition of Sn, the ductility is improved when the small rod-shaped phase forms in Mg-rich Mg–MM–Sn alloys due to the sound interface without forming any void at the end of particles after tensile test at 200°C. The result indicates that the small size rod-shaped particles can enhance the ductility while maintaining the moderate level of strength in Mg–MM–Sn alloys. [Copyright &y& Elsevier]

• The Sn added MnBi bulk magnets were prepared by hot compaction process, and it was found that it has superior coercivity compared to pure MnBi bulk magnets. • The coercivity (Hc) of Sn added MnBi bulk magnets could be effectively enhanced due to the construction of intergranular phases. • The (BH)max of 1 wt.% Sn added MnBi bulk magnet is recorded of 7.84 MGO, which shows a 7% increase compared to the pure MnBi bulk magnet. • The Sn added MnBi bulk magnet with enhanced coercivity, making it a promising candidate for the next-generation rare-earth-free permanent bulk magnets. The Sn addition MnBi bulk magnets with high density and superior coercivity (H c) were prepared by hot compaction. It was found that the added Sn was dispersed between the MnBi particles as an intergranular phase. The appropriate intergranular phase content could be beneficial in improving the H c due to the strong magnetic isolation effects. The H c of the MnBi/Sn bulk magnet was increased from 8.6 kOe to 11.5 kOe as the Sn addition contents were increased in the range of 0 wt.% to 5 wt.%. A relatively high squareness (M r / M s) of 0.91 was obtained for the 1 wt.% Sn addition Mn 56 Bi 44 bulk magnet exhibiting the maximum energy product (BH) max of 7.8 MGOe with high H c of 10 kOe at room temperature. [ABSTRACT FROM AUTHOR]

The addition of Sn in Al-Mg-Si alloys has drawn widely attention due to its strong interaction with the vacancies. In the present work, the effect of different amount of Sn addition on natural aging and precipitation hardening in Al-Mg-Si alloys are investigated. During natural aging (NA), the Sn addition can effectively suppress the clustering by capturing vacancies, and the NA hardness is gradually decreased with increasing Sn content. However, during artificial aging (AA) at 170 °C after NA, it is found that the positive effect of Sn addition is highly dependent on the Sn content. A Sn content ≤0.1 wt% can facilitate the precipitation of β″ phase due to the release of vacancies at high aging temperature. While a Sn content >0.1 wt% can result in a decrease of AA hardness. This is mainly due to the coarser and sparser distribution of β″ phases in the α-Al matrix. Besides, the excess Sn atoms preferentially form coarse primary Sn particles and Mg 2 Sn particles instead of being solute atoms in the α-Al matrix, which can deteriorate the mechanical properties of this alloy. Some Sn particles are formed at the interface of Fe-rich intermetallic particle, which probably refine the Fe-intermetallic phases in the high-Sn alloys. These results indicate that the Sn content should be accurately controlled for the Al-Mg-Si-Sn alloys with increased properties. • The positive effect of Sn addition for the Al-Mg-Si alloy highly depends on the Sn content. • A Sn content ≤0.1 wt% can facilitate the precipitation of β″ phase during AA after NA and the 0.1 wt% Sn added alloy exhibits highest peak hardness. • Sn content ≥0.2 wt% can suppress the precipitation due to the formation of coarse primary Sn particles and Mg 2 Sn particles. [ABSTRACT FROM AUTHOR]

• Sn addition can improve the high-temperature oxidation resistance of TiAl alloy. • Sn addition can change the oxide scale structure of TiAl alloy. • The presence of Ti 3 Sn phase hinders the oxygen inward diffusion and decreases the magnitude of the Ti outward flux. • The generated Al 2 O 3 oxide pegs provide mechanical locking to enhance the spallation resistance of the oxide scale. The effect of Sn addition on the oxidation behavior of high-Nb containing TiAl alloys was investigated with isothermal oxidation tests conducted in static air at 1000 °C. Sn addition can improve the high-temperature oxidation resistance of TiAl alloys by forming a protective Ti 3 Sn layer to diminish the inward oxygen diffusion. Moreover, the generated Al 2 O 3 oxide pegs provide a mechanical locking to enhance the spallation resistance. The alloy containing 3 at.% Sn exhibits superior oxidation resistance, with no spallation occurring. The lowest mass gain after being oxidized for 100 h was 3.29 mg/cm2, which is 42.1 % lower than the Sn-free alloy. [ABSTRACT FROM AUTHOR]

x wt% (x = 0, 0.03, 0.40) Sn addition in Al-Mg-Si alloys were prepared to investigate the effect of Sn on the performance of Al-Mg-Si alloys. Optical microscope (OM), scanning (SEM) and transmission electron microscope (TEM) were applied to observe the microstructure of these alloys. X-ray diffraction (XRD) was used to investigate the phase component among different alloys. Electrochemical polarization measurements and intergranular corrosion test were used to investigate the corrosion behaviors of these alloys. The experimental data shows that 0.03 wt% Sn can slightly enhance mechanical properties and corrosion resistance of Al-Mg-Si alloys because of the smaller precipitate free zones (PFZ) area and grain boundary refinement. Higher Sn addition (0.4 wt%) may cause detrimental effect on both mechanical properties and corrosion resistance of Al-Mg-Si alloys. Excess Sn tends to replace part of Si in Mg 2 Si phase and forms Mg 2 (Si,Sn) phase which is thought to be an anodic phase compared to Al matrix. Electrochemical measurements may not comprehensively reveal the overall corrosion processes, such as de-alloying process of Mg 2 (Si, Sn) phase and thus enrichment of Sn which leads to much faster dissolution of Al. • Lower Sn addition (0.03 wt%) can improve overall performance of Al-Mg-Si e by refining the grain boundary. • Higher Sn addition (0.4 wt%) in Al-Mg-Si alloys results in the formation of Mg 2 (Si,Sn) phase. • Mg 2 (Si,Sn) phase is an anodic phase compared to aluminium and can greatly decreases the corrosion resistance. • Electrochemical parameters may not comprehensively reveal the overall corrosion processes. • De-alloying process of Mg 2 (Si, Sn) phase and thus enrichment of Sn can lead to much faster dissolution of Al. [ABSTRACT FROM AUTHOR]