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以海绵钛和海绵锆为原材料通过水冷铜模电弧熔炼制备出含20%~70%Zr(质量分数)的钛锆二元合金,采用X射线衍射(XRD)、显微组织观察和差示扫描量热法(DSC)表征了热处理前后合金相组成及相转变规律。本文采用了两种热处理方法:一方面把Ti-60Zr加热到α/β转变临界温度以上(1000℃)等温后缓慢冷却至室温;另一方面研究了Ti-60Zr在α/β转变临界温度以下进行300和400℃等温热处理获得单相α相的情况。结果表明:在水冷铜模电弧熔炼获得的钛锆合金试样中除Ti-20Zr为α相以外,其他成分的合金均由α+β两相组成,其中Ti-60Zr几乎全部为β相;显微组织观察得出α型钛锆合金为针状结构,β型钛锆合金为等轴晶。平衡相图中α+β两相区的宽度直接影响过冷β相的形成能力,在同样的冷却速率下,两相区越窄的合金成分在冷却过程中越容易形成过冷β相。以10℃·min-1升温速率从室温升温至1000℃等温2 h后以5℃·min-1的冷却速率降至室温和以10℃·min-1升温速率从室温升温至400℃等温2 h后炉冷至室温两种热处理方法,均能实现Ti-60Zr合金过冷β相向α相的完全转变。
Titanium-zirconium alloy containing 20% -70% Zr (mass fraction) was prepared by sponge titanium and sponge zirconium as raw materials by X-ray diffraction (XRD), microstructure observation and differential scanning Calorimetry (DSC) characterizes the phase composition and phase transformation of the alloy before and after heat treatment. In this paper, two kinds of heat treatment methods are adopted: Ti-60Zr is slowly cooled to room temperature after being heated to a temperature above the critical temperature of α / β transition (1000 ° C) on the one hand; on the other hand, Ti-60Zr is heated below α / β transition temperature A single phase α phase was obtained by isothermal heat treatment at 300 and 400 ° C. The results show that the alloys of all the other components are composed of α + β two phases, of which Ti-60Zr is almost all β phase, except that Ti-20Zr is α-phase in the sample of titanium-zirconium alloy obtained by arc melting of water- Microstructure observation shows α-type titanium-zirconium alloy needle-like structure, β-type titanium-zirconium alloy is equiaxed. In the equilibrium phase diagram, the width of the α + β two-phase region directly affects the formability of the supercooled β phase. At the same cooling rate, the narrower alloy components in the two-phase region are more likely to form the supercooled β phase during the cooling process. The temperature was raised from room temperature to 1000 ° C at a rate of 10 ° C · min-1 for 2 h and then cooled to room temperature at a cooling rate of 5 ° C · min-1 and from room temperature to 400 ° C at a rate of 10 ° C · min-1 h after the furnace cooled to room temperature two kinds of heat treatment methods, can achieve Ti-60Zr alloy overcooling β phase α phase complete conversion.