Influence of milling parameters on the structural and phase formation in Ti-20%Al alloy through mechanical milling

Abstract

Titanium aluminides are considered the choice material for next generation propulsion systems due to their high specific strength and high temperature performance coupled with good oxidation resistance. They are considered best materials for specific applications in the aerospace and automobile industry. Their production process, however, determines the final phase in the alloy, which greatly affects their mechanical properties. The effect of the milling parameters on the particle size and the formation of phases were studied on mechanically alloyed Ti-Al powder. A high-energy ball mill (HEBM) was used to mill a mixture of CP Ti and Al to produce titanium aluminide. The alloy was produced at a fixed ball-to-powder weight ratio of 10:1 whilst varying the milling speed and milling time. The mechanically produced powders were analysed using SEM with EDX and XRD to investigate the chemical homogeneity and the formation of phases after the mechanical alloying technique. The analysis of the mechanically alloyed powders from the mill are reported in terms of the morphology evolution during different milling speed, milling time, elemental composition and the phases formed. Alloys milled at a speed of 500 rpm for a milling time range of 5–20 h revealed the formation of Ti alpha (α-Ti) and gamma phase (γ-TiAl).