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.