LIQUID PHASE DIFFUSION JOINING OF TITANIUM AND TITANIUM ALLOY

采用钛基钎料对成分为75%Ti、21%V和4%Al的β型钛合金进行了直接固相扩散连接和液相扩散连接，探讨了两种钎料的基本连接性能。结果，在固相扩散接合中，需要相当高的接合压力以获得完美的接合接头。另一方面，在使用Ti-20 Zr-20 Cu-20 Ni的钛基填充金属的液相扩散连接中，通过低压力和短连接时间实现了良好的连接接头。与耐热高温合金的液相扩散连接相比，在用钛基钎料的液相扩散连接中，用相当短的连接时间获得了与母材几乎相同的组织和成分的接头。等温凝固过程 关于我们 用透射电子显微镜对工业纯钛与钛基钎料的接头进行金相分析，结果表明：在连接温度下，纯钛、铜和镍的扩散是由扩散控制的，在接头区迅速等温凝固形成液相层;接头区在冷却过程中转变为先共析α相和共析相，形成片状和棒状组织，且在CPTi接头中，针状组织对应于Cu和Ni含量超过固溶极限的区域，随着连接过程中Cu和Ni元素的扩散，共析转变区的宽度开始增大。但随着保温时间的延长，宽度逐渐减小，最终消失。通过金相检验和扩散理论阐明了这一原因。少

Direct solid phase diffusion joining and liquid phase diffusion joining used titanium-base filler metals were carried out of beta-type titanium alloy whose compositions were of 75%Ti,21%V and 4%Al and their fundamental joinability was discussed. As a result,in the solid phase diffusion joining, an appreciably high bonding pressure was required to obtain a perfect bonded joint. On the other hand, in the ilquid phase diffusion joining with a titanuim-base filler metal of Ti-20Zr-20Cu-20Ni, a fair bonded joint was achieved by a low pressure and a short bonded time. Also an aging heat treatment after bonding was possible to be remarkably raised a tensile strength of the joint.Compared with the liquid phase diffusion joining of a heat resistant superalloy, in the liquid phase diffusion joining with the titanium-base filler metal,the joint of almost identical structure and composition with those of the base metal was obtained by considerably short bonded time. The isothermal solidification p … More rocess was exhibited to be diffusion controlled by depressant such as copper and nickel.Metallugical examination of a commercially pure titanium joint with the titaniumbase filler metal by using transmission electron microscopy revealed as follows.In holding at the joining temperature, diffusion of depressant of zircomnium,copper and nickel into the base metal, was isothermal solidified rapidly a liquid layer within joint area. The joint area was transformed into proeutectoid alpha-phase and eutectoid in cooling, which formed lameller and rod-like microstructure.Furthermore, in the joing of CPTi, an area of needle-like structure corresponded to that contained copper and nickel more than solid solute limit and according to diffusion progress of their elements during joining the width of area of eutectoid transformation increased initially. However,the width decreased with the lapse of holding time and disappered finally. This reason was clarifyed by metallugical examination and the diffusion theory. Less