为了研究用于外科植入生物材料Ti-6Al-7Nb合金的热变形行为,利用Gleeble 2000热模拟实验机对Ti-6Al-7Nb合金在750～900℃温度范围和0.001～10.000s-1应变速率范围内进行等温热压缩实验,试验在氩气保护下进行,采用金相显微镜和透射电镜观察热变形后的组织；通过计算变形激活能分析Ti-6Al-7Nb合金在热压缩过程中的变形机制.结果表明:流变应力在经历加工硬化阶段后均表现出流变软化现象,在较低应变速率ε=0.001 ～0.100 s-1时,材料的软化主要受α相动态再结晶影响；而在较高应变速率ε=1～10s-1时,材料基本不发生再结晶,其软化是由于钛合金在变形过程中的绝热效应造成的.通过Arrhenius方程计算出合金在750,800,850和900℃下的变形激活能分别为209.25,196.01,194.01和130.40 kJ·mol-1；在750～850℃下的激活能接近于α-Ti的自扩散激活能(200 kJ·mol-1),表明在750～ 850℃的变形由α-Ti自扩散参与的动态再结晶控制；在900℃下激活能略低于β-Ti的自扩散激活能(160kJ·mol-1),说明在900℃下的变形机制由β相的动态回复控制.综合考虑变形行为与组织细化因素,温度在750 ～ 850℃,变形速率在0.01 ～0.10 s-1范围为良性热加工区域.
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