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Martensitic Transformation in the Fe–Pd Alloy System

1984; Japan Institute of Metals and Materials; Volume: 25; Issue: 9 Linguagem: Inglês

10.2320/matertrans1960.25.585

2432-4701

Masaaki Sugiyama, Ryuichiro Oshima, Francisco Eiichi Fujita,

Magnetic Properties and Applications

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 martensitic transformation have been extensively studied by means of X-ray diffractometry, optical and electron microscopy. The change in surface relief associated with the fcc-fct martensitic transformation was investigated in detail by using single crystals which were made by the Bridgman method. The concentration dependence of their Ms temperatures was determined by using polycrystalline specimens, and it was shown that the fct phase is a stable low temperature one. In the cooling process, faint band regions appeared dispersedly along the {101} traces and grew with jerky motion. In the heating process, the fcc austenite regions partially arised from the fct martensite regions. The temperature hysteresis of the fcc-fct transformation was about 10 K, and cyclic treatment between cooling and heating showed a good reversibility of the process. Under the in situ electron microscope observation, plate type structures having the {101} trace appeared, though their size was two orders of magnitude smaller than that of fct bands observed by optical microscopy.In addition, it was confirmed that the fcc austenite containing palladium less than 25 at% is transformed to bcc martensite, and that the bcc martensite was clearly distinguished from the bct one.