Fabrication, microstructure and property of cellular CuAlMn shape memory alloys produced by sintering–evaporation process

Cellular CuAlMn shape memory alloys with open-cell or closed-cell structure have been manufactured successfully by sintering–evaporation process. This process consisted of mixing CuAlMn and NaCl powders, hot pressing and final high-temperature sintering to evaporate the filler material of NaCl powders. NaCl was eliminated completely during vacuum sintering, and strong metallurgical bonding in the cell walls was achieved. The pores’ structural parameter (pore size, shape, and direction) and porosity (25–70%) have been controlled effectively. The compressing deformation behavior and phase transformation behavior of the cellular CuAlMn shape memory alloy has been investigated. It was found that the maximum stress of the cellular CuAlMn shape memory alloys increased with the decrease in porosity, and the energy absorption per unit volume approached the maximum value of 35.81 MJ/m3 (the compression direction parallel to the cross-section) and 25.71 MJ/m3 (the compression direction perpendicular to the cross-section) as the porosity of the alloys was 60% and the pore size was between 355 and 800 μm.

Research highlights▶ A novel process has been developed for manufacturing cellular CuAlMn SMA. ▶ The cellular CuAlMn SMAs with oriented distribution of the elliptically shaped pores were produced. ▶ The anisotropy of the pore structure resulted in the anisotropy of mechanical properties.