Phase Evolution and Mechanical Properties of Suction Cast Ti–Fe–Co Ternary Alloys

Abstract

The current work has been undertaken with an aim to investigate the phase evolution and mechanical behaviour of Ti–Fe–Co ternary alloys. Extensive electron microscopic studies have been carried out to identify the phases present in the microstructure of the suction cast Ti–Fe–Co ternary alloys. The SEM micrographs of the investigated Ti–Fe–Co alloys reveal that the microstructures consist of eutectic matrix (L → (β-Ti)ss + Ti(Fe,Co) and/or L→(β-Ti)ss + Ti2(Co,Fe)) along with different dendritic phases ((β-Ti)ss or Ti(Fe,Co), Ti2(Co,Fe)) depending on concentration of Co. Ti70Fe20Co10 and Ti75Fe15Co10 alloys show the bimodal eutectics, ((β-Ti)ss + Ti(Fe,Co)) and ((β-Ti)ss + Ti2(Co,Fe)). The room temperature uniaxial compressive test of the Ti70Fe20Co10 ternary alloy exhibits simultaneous improvement in compressive strength (~2819 MPa) and plasticity (~8.5%) among the series of investigated Ti–Fe–Co ternary alloys. Fractography of the surface of Ti70Fe20Co10 ternary alloy reveals mixed mode of fracture. The significant outcome of the investigated Ti–Fe–Co alloys is that, the plasticity of the alloys can be improved by the development of bimodal eutectics in the microstructure or by incorporating disordered dendritic phase. © 2017, The Indian Institute of Metals - IIM.