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利用XRD、TEM、显微硬度、拉伸试验等分析方法研究双级时效热处理对Ti-25Nb-10Ta-1Zr-0.2Fe医用钛合金的显微组织和力学性能的影响。结果表明:双级时效硬度曲线在单级时效的上方并且出现明显的双峰特征。双级时效后,合金的晶内形成由片层α组成的“阶梯状”α组织,对硬度产生较大的贡献。单级时效(550℃)与双级时效((400℃,1 h)+550℃)的相析出序列分别为β→β+α″→β+α和β→β+ω→β+α″→β+α。合金性能最优的时效工艺为(400℃,1 h)+(550℃,2 h)。在此条件下合金弹性模量、抗拉强度、伸长率分别为65 GPa、845 MPa、14.3%,具有良好的综合性能。
The effect of two-stage aging heat treatment on the microstructure and mechanical properties of Ti-25Nb-10Ta-1Zr-0.2Fe medical titanium alloy was studied by XRD, TEM, microhardness and tensile test. The results show that the two-stage aging hardness curve is above single-stage aging and shows a distinct bimodal characteristic. After the two-stage aging, the “intrastructural” α-phase structure composed of lamellar α forms in the crystal of the alloy, which contributes greatly to the hardness. The phase separation of single-stage aging (550 ℃) and double-stage aging (400 ℃, 1 h) + 550 ℃) are β → β + α “→ β + α and β → β + ω → β + α” → β + α. The aging performance of the alloy was (400 ℃, 1 h) + (550 ℃, 2 h). Under these conditions, the elastic modulus, tensile strength and elongation of the alloy are 65 GPa, 845 MPa and 14.3%, respectively, which has good comprehensive properties.