LIQUID PHASE DIFFUSION JOINING OF TITANIUM AND TITANIUM ALLOY

采用钛基填充金属对成分为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，并对其基本连接性能进行了讨论。因此，在固相扩散连接中，需要相当高的连接压力才能获得完美的连接接头。另一方面，在与钛基填充金属Ti-20Zr-20Cu-20Ni的液相扩散连接中，通过较低的连接压力和较短的连接时间获得了良好的连接效果。此外，结合后的时效热处理可以显著提高接头的抗拉强度。与耐热高温合金液相扩散连接相比，钛基钎料液相扩散连接可在较短的连接时间内获得与母材组织和成分几乎相同的接头。等温凝固过程主要是由铜、镍等抑制剂控制的扩散过程。用透射电子显微镜对含钛基填充金属的商业纯钛接头进行了金相检查，结果如下。在连接温度下，锆、铜、镍等抑制剂扩散到母材中，在连接区域内迅速凝固成液层。在冷却过程中，接头区域转变为原共析α相和共析相，形成片状和棒状组织。在CPTi的连接过程中，出现了一个针状结构区域，对应于铜和镍含量超过固体溶质极限的区域，并且根据两者元素在连接过程中的扩散进程，共析转变区域的宽度开始增大。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对其原因进行了分析。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