Thermoelastic martensitic transformation in Au-Cu-Al alloys doped with Co or Ir

Thermoelastic martensitic transformations (TMT) were investigated in different Au7+x-Cu 5+y-Al4-z alloys, where x + y = z, doped with either Co or Ir. Transformation temperatures, heats of transformation, hysteresis cycles and microhardness were found strongly dependent on Au-content. The martensite self-accommodation patterns, detected using optical microscopy, after each martensite-parent phase-martensite (M-P-M) cycle only partially repeated in large grain size (?1 mm) specimens, while the same pattern was found in small grain size (?0.1 mm). Neither Co nor Ir apparently influence the nucleation sites of martensitic variants.