Ti-22Al-25Nb合金热处理后不同相含量的比较及其对合金显微硬度的影响

Comparison of Different Phase Contents in Ti-22Al-25Nb Alloy After Various Heat Treatments and Their Effects on the Microhardness of the Alloy

通过对Ti-22Al-25Nb合金设计不同的热处理工艺路线,分别得到β/B2相和O相的两相合金及β/B2相、α_(2)相和O相的三相合金;借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)和维氏显微硬度计,研究合金在不同热处理工艺下的组织演变、物相、相含量及显微硬度。结果表明:随着热处理温度的降低,由β/B2相和O相两相组成的Ti-22Al-25Nb合金中,O相和β/B2相的晶粒尺寸都逐渐增大;O相的体积分数逐渐增加,而β/B2相的体积分数逐渐减少;合金的显微硬度逐渐增加。随着热处理温度的降低,由β/B2相、α_(2)相和O相三相组成的Ti-22Al-25Nb合金中,α_(2)相和O相的晶粒尺寸都逐渐增大,而β/B2相的晶粒尺寸逐渐减小;α_(2)相和O相的体积分数逐渐增加,而β/B2相的体积分数逐渐减少;合金的显微硬度逐渐增加。这一研究结果为进一步获得综合性能优异的Ti-22Al-25Nb合金提供了数据参考。

By designing different heat treatment processes for Ti-22Al-25Nb alloy,two-phase alloys consisting ofβ/B2 and O phases,as well as three-phase alloys consisting ofβ/B2,α_(2),and O phases,were obtained.The microstructural evolution,phases,phase volume fractions,and microhardness of the alloy under different heat treatment processes were investigated by using X-ray diffraction(XRD),scanning electron microscopy(SEM),and Vickers microhardness tester.The results showed that with decreasing the heat treatment temperature,the grain size of O andβ/B2 phases in the Ti-22Al-25Nb alloy composed ofβ/B2 and O phases gradually increased;the volume fraction of O phase increased while the volume fraction ofβ/B2 phase decreased;and the microhardness of the alloy gradually increased.With decreasing the heat treat⁃ment temperature,the grain size ofα_(2) and O phases in the Ti-22Al-25Nb alloy composed ofβ/B2,α_(2),and O phases gradually increased,while the grain size ofβ/B2 phase gradually decreased;the volume fraction ofα_(2) and O phases in⁃creased,while the volume fraction ofβ/B2 phase decreased;and the microhardness of the alloy gradually increased.These results provide data reference for obtaining Ti-22Al-25Nb alloy with excellent comprehensive performance.