氧含量对Ti-4Zr-xO合金组织与力学性能的影响

Microstructures and Mechanical Properties of Ti-4Zr-xO Alloys with Different Oxygen Contents

以海绵钛、海绵锆和高纯二氧化钛为原料,采用真空非自耗电弧熔炼法制备了Ti-4Zr-xO(x=0,0.05,0.10,0.15,0.20)合金,通过差示扫描量热仪(DSC)、X射线衍射仪(XRD)、万能试验机、金相光学显微镜(OM)、显微硬度计、扫描电镜(SEM)等系统研究了氧含量对Ti-4Zr-xO合金相变温度、晶体结构、显微组织和力学性能的影响。结果表明:随着氧含量的增加,Ti-4Zr-xO合金的β转变温度(Tβ)逐渐升高,由875℃变为915℃;不同成分合金的晶体结构均为单一的密排六方α相,晶格常数随着氧含量的增加逐渐增大;合金室温组织为典型的网篮组织,其中α相形貌随氧含量的增加由片状逐渐过渡到针状,且长宽比不断增大,表现出形成针状马氏体的趋势;合金的力学性能呈现出固溶强化与细晶强化共同作用的特征:随着氧含量的增加,Ti-4Zr-xO合金的抗拉强度和屈服强度显著提高,但塑性有所下降,显微硬度的变化规律与强度保持一致,其中Ti-4Zr-0.15O合金表现出最好的综合力学性能:抗拉强度、屈服强度和断后伸长率分别为658,576 MPa和20.2%。

Ti-4Zr-xO （x = 0, 0.05, 0.10, 0.15, 0.20） alloys were prepared by non-consumable arc-melting from titanium sponge, zirconium sponge and high purity titanium dioxide, and the effects of oxygen content on transformation temperatures, microstruetures and mechanical properties of Ti-4Zr-xO alloys were investigated by differential scanning calorimetry （DSC）, X-ray diffraction （XRD）, universal testing machine, optical microscope （ OM ）, microhardness tester and scanning electron microscope （ SEM ）. The results showed that the 13 transformation temperature （ Tβ ） of Ti-4Zr-xO alloys increased by addition of oxygen, ranging from 875 to 915 ℃. All the alloys were comprised of single hcp-α phase, and lattice constants increased with oxygen content increasing. The microstruc- tures of alloys at room temperature showed typical basket weave-type structure. With oxygen content increasing, α phases showed a structure from platelet to acicular shape, and the length-width ratio also increased, presenting a potential of forming acicular-shaped martensite phase. The mechanical properties showed the typical characteristic of solid solution hardening and fine grain strengthening. The tensile strength and yield strength increased obviously with oxygen content increasing, while the plasticity decreased, and the microhardness showed a similar variation trend with the strength. The Ti-4Zr-0. 150 alloy displayed the best comprehensive mechanical properties, the tensile strength, yield strength and elongation at fracture were 658, 576 MPa and 20.2%, respectively.