钽及钽钨合金冷轧变形过程中的组织和性能

通过显微硬度分析、X射线衍射分析和TEM详细研究了钽及钽钨合金在冷轧变形过程中的组织和性能演变规律,结果表明:W在Ta中具有晶粒细化和强化作用,Ta、Ta-2.5%W和Ta-7.5%W合金在1400℃温度退火1 h后的再结晶晶粒的平均尺寸为45、20和15μm;在冷轧过程中,随着变形量的增加,钽和钽钨合金的显微硬度都逐步提高,当变形量达到99%时,Ta、Ta-2.5%W和Ta-7.5%W的显微硬度分别达到了243、309和359 HV;在Ta中添加W后,合金的位错密度会得到极大的提高,其中Ta-7.5%W合金的位错密度比Ta的高一个数量级;钽和钽钨合金各取向的晶粒中的位错密度不同,其中{200}、{211}、{222}和{110}取向的位错密度依次增大,这与Taylor因子计算的结果一致;TEM研究表明,{100}取向的晶粒中形成了位错胞结构,而{110}取向的晶粒中形成了形变带组织。

Properties and structure of Ta and Ta-W alloys during cold-roiling process

Evolution of properties and structure of Ta and Ta-W alloys in the process of cold rolling were investigated by microhardness analysis,optical microstructure(OM) observation and transmission electron microscopy(TEM).The results indicate that W has effects on strengthening and grain refinement,and the average grain size of Ta,Ta-2.5%W and Ta-7.5%W alloys is 45,20 and 15 μm,respectively.As increasing of cold-rolling reduction,microhardness of Ta,Ta-2.5%W and Ta-7.5%W alloys is improved gradually,and reaches the maximun values of 243,309 and 359 HV at reduction of 99%,respectively.The dislocation density of the alloys increases markedly by the addition of W.Especially,compared with pure Ta,Ta-7.5%W alloy is one order of magnitude higher in the density of dislocations.The dislocation density is different in cold-rolled Ta and Ta-W grains with different orientations and is consistent with the relationship {200}<{211}<{222}<{110},which is confirmed by the results of calculated Taylor factors.TEM analysis indicates that dislocation cells form in {100},while deformation bands form in {110}.