Evidence for crossover martensite in Ti50Ni45Fe5: An intermediate state between normal martensite and strain glass
1 Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, MOE Key Laboratory for Nonequillibrium Synthesis and Modulation of Condensed Matter and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University - Xi'an 710049, China
2 National Institute for Materials Science - 1-2-1 Sengen, Tsukuba 305-0047, Ibaraki, Japan
Received: 9 July 2012
Accepted: 13 November 2012
We report that the crossover from normal martensite to strain glass in the TiNi-Fe alloy system does not proceed directly as indicated by previous studies but is actually mediated by an intermediate state named crossover martensite, appearing in the crossover composition of Ti50Ni45Fe5. The martensitic transition from the parent phase to the crossover martensite is a thermodynamic phase transition, being similar to a normal martensitic transition. However, its produced crossover martensite shows an obvious kinetic feature such as a time-dependent behavior in internal friction (aging effect), resembling that of the strain glass. The microstructure of the crossover martensite exhibits a special morphology of coexisting macro-sized martensite plates and nano-sized martensitic domains. The displaying of both thermodynamic and kinetic features in the crossover martensite demonstrates that it is an intermediate state between normal martensite and strain glass; this finding provides a complete physical picture for the crossover phenomenon from normal martensite to strain glass.
PACS: 81.30.Kf – Martensitic transformations / 64.70.P- – Glass transitions of specific systems / 64.60.My – Metastable phases
© EPLA, 2012