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

Achieving precise control over α phase precipitation is crucial for obtaining ultra-high strength in metastable β-Ti alloys. However, a comprehensive understanding of how deformation products and their reversion counterparts influence α 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 α phase precipitation behavior in a metastable β-Ti alloy. After loading and reloading, SIM laths formed, and some SIM laths subsequently reversed into the β phase, introducing band-like regions with dense and parallel arranged <110> dislocations in the β phase matrix. Such dislocations resulted in a band-like area decorated with short rod-like α phase precipitates during isothermal annealing. Meanwhile, the remaining stress-induced martensite decomposed directly into α phase, forming a long α phase with a morphology similar to the original martensite. Additionally, both sides of the original SIM laths reversed during isothermal annealing, forming {332}<113>_β twins at the α/β phase interface. This divided the α phase formed in SIM laths from the α phase formed directly in the β matrix.