This study reported the development of a three-stage heat treatment for TA19 titanium alloy to obtain a ternary microstructure consisting of equiaxed, lamellar and acicular α, which were successively acquired in the first stage (I-stage), second stage (II-stage) and third stage (III-stage) treatments. The content ratio among the equiaxed, lamellar and acicular α was tailored by controlling the I-stage and II-stage temperatures. Tensile test revealed that an increase of I-stage temperature improved both ultimate strength (UTS) and elongation (EL) due to the increased content of lamellar α. However, an excessively high I-stage temperature led to a very low content of equiaxed α, coarsening of β grain and precipitation of grain boundary α, which reduced the EL. An increase of II-stage temperature resulted in an increase of UTS and a decrease of EL, because the increased content of acicular α produced a number of α/β interfaces, which strengthened the alloy but was detrimental to plasticity. The fractography analysis indicated that majority of heat treated specimens exhibited a completely ductile fracture mode, while a mixed mode of brittle and ductile fracture was observed in specimens, which was subjected to an excessively I-stage temperature.

这项研究报告了对TA19钛合金进行三阶段热处理的开发过程，以获得由等轴，层状和针状α组成的三元显微组织，它们在第一阶段（I阶段），第二阶段（II阶段）先后获得）和第三阶段（III阶段）治疗。等轴，层状和针状α之间的含量比通过控制I-阶段和II-阶段温度来定制。拉伸试验表明，由于层状α含量的增加，I阶段温度的提高改善了极限强度（UTS）和伸长率（EL）。但是，过高的I级温度会导致等轴晶α的含量非常低，β晶粒粗大化和晶界α的析出，从而降低了EL。II级温度的升高导致UTS的升高和EL的降低，因为针状α含量的增加会产生大量的α/β界面，从而增强了合金，但不利于可塑性。断口分析表明，大多数热处理过的试样表现出完全的延性断裂模式，而在标本中温度过高的试样中观察到了脆性和延性断裂的混合模式。