The effect of Si additions on the sintering and sintered microstructure and mechanical properties of Ti-3Ni alloy

Abstract

Thermodynamic predictions suggest that silicon has the potential to be a potent sintering aid for Ti-Ni alloys because small additions of Si lower the solidus of Ti-Ni alloys appreciably (>200°C by 1wt.% Si). A systematic study has been made of the effect of Si on the sintering of a Ti-3Ni alloy at 1300°C. The sintered density increased from 91.8% theoretical density (TD) to 99.2%TD with increasing Si from 0% to 2%. Microstructural examination reveals that coarse particles and/or continuous networks of Ti5Si3 form along grain boundaries when the addition of Si exceeds 1%. The grain boundary Ti5Si3 phase leads to predominantly intergranular fracture and therefore a sharp decrease in ductility..