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Abstract (Ti 1-x ,Zr x)(C 0.5 ,N 0.5)-Co cermets doped with various zirconium (x = 0, 0.05, 0.1, 0.15) were fabricated by in-situ carbothermal reduction-nitridation and liquid phase sintering-HIP treatment at 1500 °C. The microstructure, mechanical properties and oxidation resistance of (Ti 1-x ,Zr x)(C 0.5 ,N 0.5)-Co cermets were characterized by scanning electron microscope, X-ray diffraction, mechanical properties tests and high temperature oxidation experiment. The results showed that the existence of zirconium in cermets could refine the hard phase grain and improve the mechanical properties of cermets. The proper zirconium addition promoted the formation of a dense protective layer on the surface of cermets at the high temperature, which might reduce the diffusion rate of the oxygen atom and enhance the oxidation resistance of cermets. Highlights • The (Ti,Zr)(C,N)-Co cermets with the different Zr additions were fabricated. • The addition of extra Zr can inhibit the growth of hard phase particles in the sintering process. • The addition of extra Zr can enhance mechanical properties and oxidation resistance obviously. • The Zr-doped cermets hold great potential in machining and structural applications. [ABSTRACT FROM AUTHOR]

Abstract Current work reports on the development of A357 alloy composite which is reinforced with dual size SiC particles by stir casting route. Influence of different weight fractions (3% coarse+ 3% fine, 4% coarse + 2% fine, and 2% coarse + 4% fine) of dual size SiC particles on mechanical properties and wear resistance of A357 composites is the focus of this work. Hardness and tensile properties were studied for dual size composites and then were compared with A357 alloy. Microstructural study, fractured surface and worn surface investigation were carried out using optical and scanning electron microscopes respectively. Microstructural analysis showed fairly uniform dispersion of dual size SiC particles in A357 matrix with good interfacial bonding. Compared to A357 alloy, the composites showed improvement in hardness, yield, and tensile strength. In particular, composite with 4 wt. % of fine and 2 wt. % of large SiC particles displayed the highest tensile strength while composite with 4 wt. % of large and 2 wt. % of fine SiC particles exhibited high hardness and wear resistance among A357 alloy and dual particle size composites. The strengthening mechanisms that contributed to improvement in strength values were effective load transfer and dislocation strengthening due to thermal mismatch. Highlights • Uniform dispersion of dual size SiC particles in A357 matrix. • Continuous interface and good bonding between A357 matrix and dual size SiC particles. • Significant improvement in hardness and mechanical properties of dual size composites compared to A357 alloy. • Improvement in wear resistance of dual size composites compared to A357 alloy. [ABSTRACT FROM AUTHOR]

Abstract Al-6Cu-6Mg-5Sn-3Ga- x In (x = 0, 0.5, 1, 3, 5. mass. fraction) alloys were prepared using melting and casting technique. The microstructures and properties of the alloys were investigated by X-ray diffraction, scanning electronic microscope/EDX, electron microprobe analysis, Vickers hardness, compression properties, immersion tests and electrochemical measurements. The results show that the main phases of the alloys with the indium element consist of α -Al, Al 2 MgCu, Mg 2 Sn and Al-In eutectic phases. The Al-In phases segregates in α -Al grain boundaries. The gallium elements solid solution in the matrix alloys. When the addition of In contents is 1 mass.%, the hardness of the Al-6Cu-6Mg-5Sn-3Ga-1In alloy reaches to 142HV, and the compressive strength up to 582 MPa. The Mg 2 Sn and the Al-In eutectic phases are the source of the degradation reaction, and the driving force to continue is the concentration of Al in the eutectic phase. The relationship between the degradation corrosion rate and temperature, indium element content and other factors were also discussed in this paper. Graphical abstract Image 1 Highlights • Microstructure, mechanical properties and corrosion behavior of Al-6Mg-6Cu-5Sn-3Ga- x In alloys were firstly investigated. • The investigated alloys mainly consist of α -Al matrix, Al 2 MgCu, Mg 2 Sn and Al-In eutectic phase. • The investigated alloy has a maximum degradation rate reaches 98.51 mg/(cm2 h) at 93 °C. [ABSTRACT FROM AUTHOR]

The microstructures and mechanical properties of as-cast Mg-5Nd- x Al ( x = 0, 0.8, 1.6, 2.4 and 3.0 wt%) were investigated by the optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and uniaxial tension test. The addition of 3.0 wt% Al led to the most significant grain refinement of Mg-5Nd alloy with the reduction of average grain size from 448 μm to 68 μm. The grain refinement was attributed to the formation of Al 2 Nd particles as the Al 2 Nd particles acted as effective grain refiners for the Mg matrix confirmed by XRD analysis, SEM observation, and crystallography calculation. The mechanical properties of as-cast Mg-5Nd alloy increased obviously after the addition of Al. The yield strength, ultimate tensile strength and elongation of the as-cast Mg-5Nd-3.0Al alloy were enhanced by about 45.3%, 72.4% and 264.0%, respectively, compared to as-cast Mg-5Nd alloy. The improvement of mechanical properties was mainly ascribed to the refined grains and secondary phase strengthening. [ABSTRACT FROM AUTHOR]

The effect of neodymium (Nd) additions from 0 to 0.2 wt.% on microstructure, mechanical properties at room and high temperature, as well as corrosion resistance of 2A70 alloy were studied by optical microscopy (OM), scanning electron microscope (SEM), transmission electron microscopy (TEM) in this paper. The results show that appropriate addition of Nd (0.15 wt.%) refines the size and enhances the density of the aging precipitates S′ phase, which lead to the increasing of mechanical properties at room and elevated temperatures. The newly formed Al8Cu4Nd compound, dispersed along grain boundary, which hinders the movement of grain boundaries at elevated temperature and improves the high temperature performance of 2A70 alloy. Compared with traditional 2A70 alloy, the intergranular corrosion of the peak-aged alloy with 0.15 wt.% Nd has also been effectively enhanced. [ABSTRACT FROM AUTHOR]

The fabrication method of composite materials has significant influence on the mechanical properties of the materials. Establishment of proper bonding, dispersion and diffusion of reinforcement in the matrix are identified as principal characteristics which need to be taken care during the manufacturing of metal matrix composites. The current work has highlighted the impact of metal (Al) mixed dual size particle reinforcements (Al 2 O 3 (μm) & Si 3 N 4 (nm)) and the domination of silicon nitride nano particle in the composite system. The reinforcement powders were ball milled for 3 h. The matrix alloy used in this work was AA6061 which holds the applications in the construction of structures, aircraft and automobile bodies. The matrix alloy was melted and milled powders were added at 850 °C followed by stirring process. The tensile, Compression and Hardness tests were conducted to characterize the mechanical behavior of the prepared composites. The Optical Microscope and the Scanning Electron Microscopes were used to analyze the morphology of the as-cast and fractured surfaces. The composites of metal mixed reinforcements offered improved mechanical properties than the composites of unmixed reinforcement. Tensile characteristics [Ultimate Tensile Strength (72.3 MPa–153.2 MPa), yield strength (67 MPa–148 MPa), and ductility (2–8.3%)] were much influenced by pre mixed Si 3 N 4 nano particles and its volume fraction in composites. The composites with dual reinforcement have shown superior tensile behavior than single reinforcement. The compression behavior [compression strength (253–361.74 MPa)] and hardness of the composites were dominated by single reinforcement with premixed Al 2 O 3 particles. The dislocation density due to the presence of Si 3 N 4 nano particle and proper bonding of hard Al 2 O 3 particles in the matrix supported by Si 3 N 4 nano particles were observed as strengthening mechanism in the composites with dual reinforcement. [ABSTRACT FROM AUTHOR]

The single-phase TiNbZrMo x (x = 0, 0.3, 0.5, 0.7, 1) high-entropy alloys (HEAs) were prepared by arc melting. The relation between molybdenum, microstructure, mechanical properties and wear resistance was investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM), universal tensile tester, hardness tester, friction tester, and wear tester. The results showed that TiNbZrMo x alloys were composed of a single BCC phase. With the increase of Mo elements, the crystallite size of the as-cast alloy decreased first and then increased, both the alloy strength and hardness were increased and compressive strain plasticity was decreased. TiNbZrMo 0.5 has the best comprehensive performance with a yield strength of 1.0 GPa, compressive strength of 1.3 GPa, and hardness of 429 HV; compared with TiNbZrMo 0 , yield strength increased by 77.32%, compressive strength increased by 25.14%, and hardness increased by 70.24%; and its specific wear rate decreased by 50%, while it's compressive plasticity only decreased by 5%. • The addition of appropriate amounts of molybdenum improves the strength, hardness and wear resistance of TiNbZrMo x HEAs. • Compared to TiNbZr, TiNbZrMo 0.5 has the best overall performance. • The main wear mechanisms of TiNbZrMo x (x = 0, 0.3, 0.5, 0.7, 1) are abrasive wear and oxidative wear. [ABSTRACT FROM AUTHOR]

The effects of Gd addition on microstructure, mechanical properties and corrosion behavior of degradable Mg-17Al-7Cu-3Zn- x Gd ( x = 0, 1, 2, 3. weight fraction) alloys were investigated using optical microscope, scanning electronic microscope equipped with energy dispersive spectroscope, compression tests, electrochemical measurements, and immersion tests. The main phases in the alloys with rare earth Gd consist of α-Mg、β-Mg 17 Al 12 、T (Al 13 Mg 14 Cu 5 Zn 1 ) and (Al,Mg) 3 Gd. The Mg-17Al-7Cu-3Zn-1Gd alloy exhibits the maximum yield strength of 302 MPa, ultimate compression strength of 440 MPa, and degradable corrosion rate of 0.21 mm/day. The significant improvements in compression strength and degradable rate were attributed to the dense network-shaped β-Mg 17 Al 12 phase forming on the grain boundaries of the α-Mg matrix and tubular-shaped T phase. The cuboid-shaped (Al, Mg) 3 Gd phases refine the grain size, and thus improve the mechanical properties and corrosion resistance of the based alloys. [ABSTRACT FROM AUTHOR]

Cu-1 wt%Al 2 O 3 composite powder, prepared by mechanical milling and consolidated by spark plasma sintering to have about 98–99% of theoretical density, were characterized by scanning electron microscope, focused ion beam microscope, X-ray diffraction, nanoindentation and transmission electron microscope. The mechanically milled powders, upon consolidation, exhibited a finer grain size of 2 μm. Tensile deformation behavior of this composite, at ambient temperature but over the strain rates of 10 −4 s −1 to 5 × 10 −2 s −1 , exhibited typical manifestations of dynamic strain ageing in the form of serrations and negative strain rate dependence of flow stress. The yield and ultimate tensile strengths, and so also the elongation decrease gradually with increase in strain rate. Such variation was also shown by nanoindentation hardness as a function of loading rate over 1–100 mN/s. The observed results are explained by the dislocation structure evolved from its interaction with Al 2 O 3 dispersoids and impurity atoms like Fe, C and O coming from the powder processing. [ABSTRACT FROM AUTHOR]

To optimize the mechanical properties of Ti(C,N)-based cermets used as tool materials, the cermets with different Ni–Co binder contents and Co/(Ni + Co) weight ratios were prepared. The effects of metal binder content and Co/(Ni + Co) ratio on the microstructure and mechanical properties of Ti(C,N)-based cermets were investigated by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and measuring the transverse rupture strength (TRS), Vickers hardness ( HV ) and fracture toughness ( K IC ). The experimental results reveal that increasing Ni–Co binder content can increase the thickness of rim phases by improving the solid solution reaction and the wetting of hard phases. The cermets with 25 wt.% binder addition present good comprehensive mechanical properties, which is attributed to the moderate rim phases and uniformly distributed Ti(C,N) grains. The Co/(Ni + Co) weight ratios in binder have a great influence on the grain sizes and microstructure features of Ti(C,N)-based cermets, in virtue of the synergic effects between the wettability of Co and the solubilizing capacity of Ni on hard phases. The cermets with pure Co as binder exhibit optimal mechanical properties with a TRS of 1767 ± 81 MPa, a hardness of 12.26 ± 0.10 GPa and a K IC of 8.40 ± 0.47 MPa m 1/2 , which meet the requirements for tool materials. And the cermets with a Co/(Ni + Co) ratio of 0.2 have the second best mechanical properties with a TRS of 1848 ± 201 MPa, a hardness of 11.12 ± 0.40 GPa and a K IC of 9.43 ± 0.54 MPa m 1/2 , in which the lower hardness can be further improved by optimizing the compositions and sintering process. [ABSTRACT FROM AUTHOR]

A suitable sintering method is important to obtain the Ti(C,N)-based cermets with superior properties. In this paper, Ti(C,N)-based cermets were fabricated by hot-pressing sintering (HP) and conventional pressureless sintering (PLS) technology, respectively, to investigate the influence of different sintering methods on the microstructure and mechanical properties of cermets materials. The microstructure, fracture morphology, indention cracks and phase composition were observed and detected using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The transverse rupture strength (TRS), Vickers hardness ( HV ) and fracture toughness ( K IC ) were also measured. The results reveal that all of the Ti(C,N)-based cermets exhibit core–rim microstructures with black cores, white cores and grey rims embedded into metal binder phases. The grain size of the samples fabricated by HP is much finer and the structure is more compact than those fabricated by PLS, while there exist pores in the HP sintered samples. The sintering process has no influence on the phase composition of cermets, but affects the phase content and crystallinity. The samples fabricated by PLS present higher transverse rupture strength, fracture toughness and density than samples fabricated by HP. However, the HP sintered samples possess a higher hardness. [ABSTRACT FROM AUTHOR]

Al-Zn-Mg-Cu alloy, as an important lightweight structural material in the aerospace field, has ushered in a broader application space and proposed higher performance requirements. This paper presents the experimental investigation of the effect of Zr content on the microstructure refinement and performance improvement of cast Al-5.8Zn-2.3Mg-1.7Cu alloy, aiming to optimize the additional amount of Zr, refine the alloy grains, and improve the microstructure uniformity and mechanical properties. The chemical component, phase, and microstructure were observed by inductively coupled plasma, X-ray diffraction, optical microscope and scanning electron microscope; the hardness and mechanical properties were measured by Brinell hardness tester and tensile testing machine. The addition of different contents of Zr into the alloy can form fine dispersed or primary coarse Al 3 Zr phase, which has a significant effect on the microstructure and mechanical properties of the alloy. The results indicate that the addition of 0.05 wt% Zr does not significantly improve the grain refinement and mechanical properties, but the Brinell hardness reaches the maximum. As the Zr content rises, the grain refinement effect becomes more obvious, while the mechanical properties first increase and then decrease. The addition amount reaches 0.20 wt%, the second dendrite arm spacing is the smallest, the ultimate tensile strength, yield strength and elongation at room temperature reach the maximum of 296.74 MPa, 249.41 MPa and 8.26%, respectively. When the amount of Zr added exceeds 0.20 wt%, the existence of coarse and brittle primary Al 3 Zr phase reduces the mechanical properties, and the fracture morphology changes from ductile to brittle intergranular fracture. • Zr element can refine the alloy grains. The higher the amount of Zr added, the more obvious the grain refining effect. • With the increase of Zr content, the mechanical properties of the alloy will first increase and then decrease. • When Zr content is excessive, the Al 3 Zr phase is the reason for the decrease in toughness. [ABSTRACT FROM AUTHOR]

In this research work, the 6111Al reinforced by rare earth element Er was subjected to severe plastic deformation with different rolling reduction ranging from 50%, 70%–90% respectively. Continuous deepening of the dynamic recrystallization occurred during the increment on rolling deformation and the average size of α-Al grains decreased to 7.9 μm eventually. The nanosized Al 3 Er particles were characterized by the combined function of inhibiting and promoting the DRX at the same time during the rolling process. And the competitive relationship between the driving force and the restraining force has been studied via systematic calculation here. A noticeable enhancement on 6111Al–Er alloy has been obtained with YS, UTS and elongation increasing to 359 MPa, 380 MPa and 27.4% respectively when the rolling deformation reached to 90%, which was attributed to the synergistic strengthening effect induced by the fine grain strengthening and the Orowan strengthening mechanisms. The evolution of microstructure was characterized by the equipments including Electron backscattered diffraction (EBSD), Scanning electron microscope (SEM) and High resolution transmission electron microscope (HRTEM). • Multi round dynamic recrystallization occurred during the rolling process. • Al 3 Er particles possess combined function of inhibiting and promoting the DRX. • Mechanical properties of 6111Al is enhanced notably by rolling and Er addition. [ABSTRACT FROM AUTHOR]

In the quest of novel, reasonable and effective reinforcement, it is very hard to find rare combination of materials which attempts to accord and benefit each other. The exhausted waste spent catalyst from petroleum industries is experimented as a reinforcement obliging to the concept of reuse and recycle. In this investigation, aluminium metal matrix nano composite is to be synthesized by double stir casting method. Pure aluminium and Spent Alumina Catalyst (SAC) is chosen as matrix and primary reinforcement respectively. Nano CuO is added as secondary reinforcement to enhance the mechanical properties of aluminium spent alumina catalyst composite. The composites are synthesized as such, 10% SAC is reinforced to pure aluminium and the amount of nano CuO is varied 0.5%, 0.75%, 1%. Microstructural characteristics of cast composites and tensile samples is studied under Scanning Electron Microscope. There is no clogging of reinforcement materials (nano CuO and SAC) in the aluminium matrix. The mechanical properties of the composites are determined and compared with pure aluminium. There is an impact of dual reinforcement on aluminium matrix which is evident by the improvement in the mechanical properties of the composite. The optimum composition is Al + 10%SAC +1%nano CuO, which resulted in maximum increase in hardness (77%) and tensile strength (78%). • Reuse of Spent Alumina Catalyst (petroleum industrial waste) as a reinforcement. • Synthesis of Aluminium nano composite with Dual Reinforcement (Spent Alumina Catalyst + nano Copper Oxide) by Stir Casting. • Evaluation of microstructure and mechanical properties of newly synthesized composite. • Enhanced mechanical Properties. [ABSTRACT FROM AUTHOR]