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

Abstract

Ultrafine eutectic alloys have been developed in Ti - Ni , Ti - Fe and Ti -( Ni , Fe )- Sn alloys. The Ti 76 Ni 24 and ( Ti 74 Ni 26)97 Sn 3 ultrafine eutectic alloys consist of a mixture of α- Ti and Ti 2 Ni phases, and β- Ti ( Sn ) and Ti 2 Ni phases, respectively, whereas the Ti 70.5 Fe 29.5 and ( Ti 70.5 Fe 29.5)97 Sn 3 alloys are composed by a mixture of β- Ti ( Sn ) and FeTi phases with relatively spherical colony. The compression tests of Ti 76 Ni 24, ( Ti 74 Ni 26)97 Sn 3 and Ti 70.5 Fe 29.5 ultrafine eutectic alloys reveal a strength of 1400 ~ 1800 MPa with very limited plastic strain of 0.1 ~ 1%. On the contrary, a ( Ti 70.5 Fe 29.5)97 Sn 3 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.