Effect of α″ martensite on the microstructure and mechanical properties of beta-type Ti-Fe-Ta alloys
Health, Engineering and Science
School of Engineering
This work aimed to investigate the effect of Fe and Ta contents on the β. →. α″ martensitic transformation as well as the microstructure and mechanical properties of the as-cast designed Ti- xFe- yTa (x= 8, 9, 10. wt% and y= 0, 2, 5, 8, 9, 10. wt%) alloys. The microstructure of all alloys substantially consists of β and α″ phases. However, the addition of more Fe and Ta β-stabilizers to Ti-8Fe alloy reduced the likelihood to form α″ martensite during quenching, hence decreasing the volume fraction of α″ phase and finally reaching 3% in Ti-10Fe-10Ta alloy. The microstructural studies results revealed that except for Ti-8Fe and Ti-9Fe-2Ta, all alloys with high Ta content present a dendritic microstructure. It is noteworthy noting that all alloys possess higher Vickers hardness and compressive yield stress values than those of CP-Ti and Ti-6Al-4V. However, Ti-10Fe-10Ta alloy with the least amount of α″ martensite phase and dominant β phase structure exhibits the lowest elastic modulus and highest plasticity. It was concluded that further decrease in modulus of elasticity can be achieved through stabilizing single β phase by designing composition of Ti-Fe-Ta alloy.