热处理对富锆α型TiZrAl合金组织和性能的影响

Effect of heat treatment on microstructures and properties of Zr-richαTiZrAl alloy

针对2种富锆α型钛合金(Ti_(60)Zr_(40))_(97)Al_(3)(质量分数/%,下同)和(Ti_(50))Zr_(50)_(97)Al_(3),利用光学显微镜(OM)、差示扫描量热仪(DSC)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)及室温拉伸等实验手段,分析研究了不同热处理工艺下2种合金的组织和性能。结果表明,经850℃/40 min退火后,合金为α网篮组织,并在α相间留有少量网状β相;经850℃/40 min水冷淬火,形成细针状α'马氏体;经850℃/40 min淬火+600℃/4h时效后,在淬火中形成的细小针状α'马氏体转变成α相,然而马氏体转变不完全,形成α+α'_(remain)组织。T40Z3A合金的拉伸屈服强度可达1100 MPa,并具有7%良好的伸长率;T50Z3A合金虽然具有更高的强度,但其塑性较差。分析表明,由于更高的Zr含量,T50Z3A合金在退火后具有更多的网状β相、淬火时效后具有更多残留α'马氏体相,导致其抗拉强度较高、塑性较差。

The microstructures and properties of two kinds of zirconium-enrichedαalloys(Ti_(60)Zr_(40))_(97)Al_(3)(mass fraction/%,the same below)and(Ti_(50)Zr_(50))_(97)Al_(3) via different heat treatments were investigated and analyzed based on optical microscope(OM)observation,differential scanning calorimetric(DSC)measurement,X-ray diffraction(XRD)measurement,scanning electron microscope(SEM)observation and tensile tests at room temperature.The results show that after 850℃/40 min annealing,microstructures consisting of basket-weaveαphase and a small amount of reticularβphase are formed in the alloys.After 850℃/40 min quenching,the acicularα'martensite phase is formed.After 850℃/40 min quenching and then 600℃/4 h aging,a large part ofα'martensite phase converts intoαphase,and the microstructures of the alloys consist ofαandα'remain phases.The yield strength of the T40Z3A alloy can reach 1100 MPa,with a favourable tensile elongation of 7%.The T50Z3A alloy exhibits higher strength but lower ductility than those of the T50Z3A alloy.Due to the higher content of Zr element,the T50Z3A alloy has more reticularβphase after annealing and more remainingα'martensite phase after quenching and aging,which results in higher strength and lower ductility.