Stable strain hardening behavior of Ti-4Al-5Mo-5V-5Cr-1Nb alloy during plastic deformation

Strain hardening is crucial to the formability and reliability of structural materials, however, such capacity will be exhausted as strain increases. In current work, a stable strain hardening character is found in the compression of Ti-4Al-5Mo-5V-5Cr-1Nb alloy up to 0.4 strain. Microstructural characterization on deformed samples reveals the development of multiscale α′′ lath frames. The stable strain hardening behavior is understood via unveiling the roles of α′′ lath during deformation. It is noted that these α′′ laths impede dislocations and reduce their mean free path as strain increases. Meanwhile, a high density of dislocations can be observed within these nanoscale α′′ laths, indicating they are also involved into deformation. Such a strain accommodation mechanism greatly relieves the stress concentrated at β/α′′ interfaces enabling the resistance to crack initialization.