Effect of stress-induced martensites and reverse-induced dislocations on α phase precipitation behavior in a metastable β-Ti alloy

Achieving precise control over alpha phase precipitation is crucial for obtaining ultra-high strength in metastable beta-Ti alloys. However, a comprehensive understanding of how deformation products and their reversion counterparts influence alpha phase precipitation behavior in these exceptional alloys remains elusive. This study explores the influence of stress-induced martensite (SIM) and its reversion-induced dislocations on the alpha phase precipitation behavior in a metastable beta-Ti alloy. After loading and reloading, SIM laths formed, and some SIM laths subsequently reversed into the beta phase, introducing band-like regions with dense and parallel arranged <110> dislocations in the beta phase matrix. Such dislocations resulted in a band-like area decorated with short rod-like alpha phase precipitates during isothermal annealing. Meanwhile, the remaining stress-induced martensite decomposed directly into alpha phase, forming a long alpha phase with a morphology similar to the original martensite. Additionally, both sides of the original SIM laths reversed during isothermal annealing, forming {332} <113>(beta) twins at the alpha/beta phase interface. This divided the alpha phase formed in SIM laths from the alpha phase formed directly in the beta matrix. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.