Design and tensile properties of a bcc Ti-rich high-entropy alloy with transformation-induced plasticity

<p>A new bcc Ti-rich high-entropy alloy (HEA) of composition Ti₃₅Zr_27.5Hf_27.5Nb₅Ta₅ was designed using the ‘d-electron alloy design’ approach. The tensile behavior displays a marked transformation-induced plasticity effect resulting in a high normalized work-hardening rate of 0.103 without loss of ductility when compared to the reference composition Ti₂₀Zr₂₀Hf₂₀Nb₂₀Ta₂₀. In this paper, a detailed microstructural analysis was performed to understand the deformation process, revealing architectural-type microstructures and a high volume fraction (65%) of internally twinned stress-induced martensite <i>α</i>^″ after mechanical testing. This study opens the way to mechanical properties optimization and enhancement of titanium-based HEAs by combining multiple alloying designs.</p> <p><b>IMPACT STATEMENT</b></p> <p>For the first time, proof is given that transformation-induced plasticity was triggered in a bcc refractory high-entropy alloy, leading to a twofold increase in the normalized work-hardening rate.