(中国科学院 金属研究所, 沈阳 110016)
摘 要: 通过对亚稳β-Ti2448合金进行Gleeble热模拟压缩实验，研究其在单相β区的高温变形机制。结果表明：Ti2448合金的高温变形机制与应变速率有关，在较低应变速率(10−3~10−1 s−1)范围内，合金表现出初始应力峰值，随后逐渐软化直到达到稳态流变；其变形机制主要是形核和新晶粒长大的不连续动态再结晶(DDRX)。在较高的应变速率(1~63 s−1)范围内，合金首先表现出明显的硬化，随后略有软化，最后达到稳态；其变形机制主要是位错滑移主导的塑性变形，位错与晶界以及亚晶界之间的相互作用促使小角度晶界向高角度晶界的转变，表明变形机制为连续动态再结晶(CDRX)。
关键字: 亚稳β-Ti2448合金；动态再结晶(DRX)；位错结构
（Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:The deformation mechanism of metastable β-Ti2448 alloy at elevated temperature was investigated by compression tests using Gleeble 3800 isothermal thermal simulator. The result shows that the deformation mechanism of Ti2448 at elevated temperature is associated with strain rate. In the lower strain rate range (10−3−10−1 s−1), the alloy exhibits stress peak in the initial stage and gradually softens subsequently until steady-flow. The primary mechanism of Ti2448 alloy at lower strain rate is discontinuous dynamic recrystallization (DDRX), with the characteristic of nucleation and new grain growth. In the higher strain rate range of 1~63 s−1, the alloy presents obvious hardening firstly, then slight softening and steady-state finally. The leading mechanism of Ti2448 alloy at higher strain rate is plastic deformation dominated by dislocation slipping. The interaction between dislocations and grain or sub-grain boundaries induces the transformation of low angle boundaries into high angle boundaries, which indicates continuous dynamic recrystallization (CDRX).
Key words: metastable β-Ti2448 alloy; dynamic recrystallization (DRX); dislocation structure
