MARTENSITIC TRANSFORMATION IN THE Fe-Pd ALLOY SYSTEM.

Abstract

In Fe-Pd alloys containing about 30 at% palladium, fcc-fct thermoelastic transformation exists and the fct martensite phase is further transformed non-thermoelastically to the bct martensite phase. The morphology and structure of the transformation have been studied by X-ray diffractometry, optical and electron microscopy. The change in surface relief associated with the fcc-fct martensitic transformation was investigated by using single crystals. The concentration dependence of the Ms temperatures was determined using polycrystalline specimens. The temperature hysteresis of the fcc-fct transformation is about 10 K, and cyclic treatment between cooling and heating showed good reversibility. In addition, it is confirmed that the fcc austenite containing less than 25 at% palladium is transformed to bcc martensite, and that the bcc martensite is different from the bct one.