Mechanical behavior and deformation mechanisms of Ti-2.5Cu alloy reinforced by nano-scale precipitates at 293 and 77 K

Nano-scale precipitates were obtained in Ti-2.5Cu alloy after solution and aging treatment, and the precipitates were determined to be Ti₂Cu intermetallic compound and arrange along three directions [1̄ 2 2̄], [2 1 1̄]. and [2 1 1̄]. Tensile tests and low-cycle fatigue tests were conducted at 293 and 77 K. The results show that Ti-2.5Cu alloy possesses higher ductility and longer low-cycle fatigue life at 77 K than at 293 K, which can be interpreted by the model of twinning induced plasticity (TWIP). The microstructures indicate that slipping is predominant deformation mode at 293 K, and twinning becomes more active at lower temperature or under push-pull cyclic loading. The precipitates hinder the movement of dislocation obviously, while have little effect on twinning process. There are five types of twins identified in deformation of Ti-2.5Cu alloy reinforced by nano-scale Ti₂Cu intermetallic compound, which use {1 1 2̄ 4 }, { 10 1̄ 1 }, {1 1 2̄ 2 } and {1 1 2̄ 1 } twins.