MICROSTRUCTURAL EVOLUTION AND MECHANICAL PROERTIES OF Ti-(Ni, Fe)-Sn ULTRAFINE EUTECTIC ALLOYS

摘要

Ultrafine eutectic alloys have been developed in Ti-Ni, Ti-Fe and Ti-(Ni, Fe)-Sn alloys. The Ti76Ni24 and (Ti74Ni26)97Sn3 ultrafine eutectic alloys consist of a mixture of a-Ti and Ti2Ni phases, and β-Ti(Sn) and Ti2Ni phases, respectively, whereas the Ti70.5Fe29.5 and (Ti70.5Fe29.5)97Sn3 alloys are composed by a mixture of β-Ti(Sn) and FeTi phases with relatively spherical colony. The compression tests of Ti76Ni24, (Ti74NJ26)97Sn3 and Ti70.5Fe29.5 ultrafine eutectic alloys reveal a strength of 1400 ～ 1800 MPa with very limited plastic strain of 0.1 ～ 1%. On the contrary, a (Ti70.5Fe29.5)97Sn3 alloy exhibits high strength of 2270 MPa with enhanced plastic strain of 3.1%. Based on these results, it is feasible to suggest that the eutectic morphology and interfacial coherency between the Ti solid solution and intermetallic phases influence to control the macroscopic plasticity of the Ti-Ni and Ti-Fe ultrafine eutectic alloys.