PHASE TRANSFORMATIONS IN RAPIDLY SOLIDIFIED TiNi SHAPE MEMORY ALLOYS

ＰＨＡＳＥＴＲＡＮＳＦＯＲＭＡＴＩＯＮＳＩＮＲＡＰＩＤＬＹＳＯＬＩＤＩＦＩＥＤＴｉＮｉＳＨＡＰＥＭＥＭＯＲＹＡＬＬＯＹＳＷａｎｇ；ＳｈｉｄｏｎｇＷｕ；Ｘｉａｏｚｈｅｎ（ＡｎａｌｙｔｉｃａｎｄＴｅｓｔｉｎｇＣｅｎｔｅｒ．ＳｏｕｔｈｅａｓｔＵｎｉｖｅｒｓ...

The transformation behaviors associated with R-phase and martensitic transformations in rapidly solidified TiNi shape memory alloys have been studied systematically using differential scanning calorimetry, X-ray diffraction, etc. It was found that rapid solidification more significantly depresses the temperature ranges of R-phase and martensitic transformations than solution treatment and makes it possible that the martensite transformation is separated from R-phase transformation. After aging the rapidly solidified Ni-rich TiNi binary shape memory alloy the martensite can be separated from the R-phase in not only the forward but also reverse transformations. With increasing aging time both the forward and reverse transformation temperature ranges of martensite and R-phase shift to high temperature.