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Porous Cu–Al–Ni shape memory alloys (SMAs) are fabricated via powder metallurgy method using Cu, Al, Ni powders and Cu–Al–Ni alloy powder as raw materials, respectively. It is found that the two kinds of specimens have similar macroscopic morphologies: connected pores are uniformly distributed in the Cu–Al–Ni matrix, forming a 3D network structure. By comparison, the specimen fabricated using alloy powder has much finer microstructures than the specimens fabricated using Cu, Al, Ni powders. After adding Ce element to the latter, the microstructure of the Cu–Al–Ni matrix is significantly refined because of the formation of Ce‐rich particles. Damping tests show that the latter has superior damping capacity than the former. With the increase of Ce content, the damping of the latter increases first and then decreases. When the Ce content reaches 0.05 wt%, the highest damping can be achieved. Correlated mechanisms are discussed based on the microstructural observations. [ABSTRACT FROM AUTHOR]

A novel preparation process consisting of four stages has been successfully developed to produce Ti 52 Al 48 (at.%) intermetallic compound porous material based on the combined action of making pores arising from the replication of space holders and Kirkendall effect. The porous TiAl exhibits a typical double pore structure, millimeter pores distributed in matrix and micrometer pores embedded in pore walls and struts. Moreover a complete open-cellular structure and homogeneous distribution can be observed and the porosity even more than 80% can be easily achieved. Compressive tests and micrograph observation illustrate that the most suitable sintering temperature should be around 1400 °C for the porous TiAl. [ABSTRACT FROM AUTHOR]

High speed steel T15 particle reinforced copper matrix composites were prepared using powder metallurgy. A systematic investigation was conducted into the effects on the microstructure and mechanical properties of the composites of the sintering temperature, T15 hard particle content, and particle size. The results indicate that the grain size is efficiently refined by the addition of T15 hard particles. The decrease in grain size of 10 wt% T15/Cu composite is from 6.87 μm to 1.34 μm at the same sintering temperature, and the grain size is proportional to both the sintering temperature and the size of hard particles. As the sintering temperature increases, the relative density and hardness of the composite gradually increase, while the yield strength initially increases and then declines. When sintered at 790 °C, the 10 wt% T15/Cu composite achieved a maximum yield strength of 160.1 MPa, which is 178.9 % and 30.6 % higher than that of pure copper and 10 wt% TiC/Cu composites, respectively. There are no visible cracks after compression, and a good balance of strength and toughness is achieved. Meanwhile, the primary contributions of strengthening mechanisms such as grain refinement, thermal expansion mismatch and load transfer to the mechanical properties of T15/Cu composites were analyzed. It is anticipated that this will establish a foundation for the preparation and application of high-performance copper matrix composites reinforced with metal particles. • High speed steel T15 particle reinforced copper matrix composites were prepared using powder metallurgy. • The addition of T15 hard particles can effectively refine the grain size. • The mechanical properties of the T15/Cu composites showed a significant improvement. • The strengthening mechanism of T15/Cu composites was quantitively analyzed. [ABSTRACT FROM AUTHOR]

To address the issues of existing powder metallurgy particle reinforced composites, such as poor wettability between ceramic reinforcement and Al matrix, the toxicity of quasicrystal, the compositional limitations of high entropy alloy, and poor thermal stability of amorphous alloy reinforcement, etc. Al matrix composites reinforced with Co-based hard particles (M7) were synthesized by a powder metallurgy process. The effects of sintering temperature, M7 hard particle content, and particle size on the microstructure and mechanical behavior of the composites were investigated. The results show that as the sintering temperature rises, the interdiffusion reaction between M7 particles and Al matrix is enhanced, the diffusion layer becomes thicker, the in-situ generated intermetallic compounds such as Al 3 Ni 2 , Al 13 Cr 2 , Co 2 Al 9 and Al 72.5 Co 16.5 Ni 11 become more abundant, and parts of M7 particles gradually dissolve in the Al matrix and the interdiffusion layer disappeared. When the sintering temperature was raised from 580°C to 640°C, the microhardness and yield strength were improved from 23.9 to 34.7 HV 0.1 and 40.9–175.2 MPa, respectively. The composites' microhardness and strength increase as the M7 particle content increases. Meanwhile, the smaller the particle size, the greater the microhardness and yield strength. The strengthening mechanism of M7/Al composites is mainly attributed to the synergistic effects of the in-situ generated multiphase intermetallic compounds strengthening, solid solution strengthening, and M7 hard particles dispersion strengthening. Furthermore, the M7/Al composites' microhardness and strength were respectively 27.6% and 146.1% higher than those of the SiC/Al composites containing the same size and content of SiC particles, which is mainly due to the good interfacial wettability between M7 and Al matrix. It indicates that metal-based hard particles could be better alternative reinforcements to produce high performance composites. • Al matrix composites reinforced with Co-based hard particles were synthesized by PM. • There was a significant improvement in the mechanical properties of the M7 /Al composites. • The synergistic reinforcement mechanism for M7 /Al composites is proposed. [ABSTRACT FROM AUTHOR]