Fabrication of shape memory alloys using the plasma skull push–pull process

Abstract

In this work, the fabrication of shape memory alloys (SMAs) through the use of the plasma skull push–pull (PSPP) process was studied. In this process, small quantities of metallic elements can be quickly melted on a copper crucible using a rotating plasma torch and injected into a metallic mold. In order to validate the utilization of the PSPP process to produce SMA, several Ni–Ti-based and Cu–Al-based binary, ternary and quaternary alloys were tested. It was verified that five melts and re-melts of the SMA before injection are enough to obtain a homogeneous product. The obtained SMAs were characterized by optical microscopy and microhardness measurements. The thermoelastic martensitic transformation at the origin of the shape memory effect (SME) was studied via electrical resistance as a function of temperature and differential scanning calorimetry (DSC). All studied SMAs were shown to undergo a thermoelastic transformation, thus demonstrating the viability of the PSPP process to fabricate a great variety of SMAs.