Duplex-structured TC21 alloy samples were first solution-treated at a higher temperature in the α + β region (940°C) with furnace cooling (FC), air cooling (AC), and water cooling (WC), followed by a second-stage solution treatment at a lower temperature in the α + β region (900°C), and then finally aged at 590°C. The effects of the morphology and quantity of a phases on the structure and properties of the TC21 alloy after the different heat treatments were analyzed. The in-situ tensile deformation process and crack propagation behavior were observed using scanning electron microscopy (SEM). The quantity of equiaxed a phases as well as the thickness of lamellar a phases reduced, the tensile strength increased firstly and then decreased, the elongation decreased with the increasing cooling rate after the first-stage solution treatment. The amount and size of lamellar a phases increased after the second-stage solution treatment because of sufficient diffusion of the alloying elements, thereby leading to increased tensile strength. The amount of dispersed a phases increased after the third-stage aging treatment owing to the increase in the nucleation rate, resulting in a noteworthy strengthening effect. After the third-stage aging treatment, the first-stage FC sample exhibited better mechanical properties because it contained more equiaxed α and β_trans phases than the first-stage AC and WC samples.

首先，在较高的温度下，在α+β区域（940°C）中采用炉冷却（FC），空气冷却（AC）和水冷却（WC）对双相结构的TC21合金样品进行固溶处理，然后进行第二次在较低温度下在α+β区域（900℃）进行阶段固溶处理，然后最终在590℃时效。分析了不同热处理后相的形态和数量对TC21合金组织和性能的影响。在原位使用扫描电子显微镜（SEM）观察了拉伸变形过程和裂纹扩展行为。在第一阶段固溶处理后，等轴晶相的数量减少，层状α相的厚度减少，抗拉强度先增加后降低，伸长率随冷却速率的增加而降低。在第二阶段固溶处理之后，层状α相的数量和尺寸由于合金元素的充分扩散而增加，从而导致拉伸强度增加。在第三阶段时效处理之后，由于成核速率的增加，分散的α相的量增加，从而导致显着的强化效果。经过第三阶段的时效处理_反相比第一阶段的AC和WC样本要好。