Thermomechanical Characterization of a TiPdNi High Temperature SMA under Tension

The focus of this paper is the study of tensile work characteristics and the transformation behavior of a High Temperature Shape Memory Alloy (HTSMA) by thermomechanical characterization at temperatures ranging from 200 to 500°C. In order to investigate the above issues, a nominal composition of Ti50Pd40Ni10 HTSMA was used. The alloy was fabricated using a vacuum arc melting technique. The melt was cast and hot rolled followed by cutting of tensile specimen using Electrode Discharge Machining (EDM). A high temperature experimental setup was developed on a load frame to test the material at high temperatures under constrained actuation conditions. The stability of the material response under cyclic actuation was also investigated. The observations from the tests are presented in this paper. Microprobe analysis was performed on the as-cast and rolled material to study the composition. The material was also studied by X-ray diffraction (XRD) and optical microscopy before and after testing. Certain key observations about the material response are discussed specifically, in terms of transformation behavior, recoverable strains under various applied total strains, and cyclic thermomechanical behavior.