氢对多孔Ti6Al4V合金扩散连接质量的影响

The effects of hydrogen on quality of diffusion bonding for porous Ti6Al4V alloy

文章通过采用Gleeble1500热模拟机进行真空扩散连接试验,研究了氢对多孔Ti6Al4V合金扩散连接质量的影响,并应用光学显微镜、扫描电镜(Scanning electron microscope,SEM)及电子万能试验机对界面孔洞弥合率、界面组织形貌、抗弯强度和断口形貌进行分析。结果表明,真空扩散连接后的孔洞弥合率随着原始氢含量的增加而升高,但升高的趋势逐渐平缓;扩散连接后,原始氢含量较低的试样室温组织为α+片状(α+β),原始氢含量高的试样室温组织为条状α+等轴状(α+β);室温下,在一定的氢含量范围内,氢元素在多孔合金中以间隙固溶和氢化物状态存在,均起到了强化作用,使扩散连接后材料抗弯强度增加;随着剩余氢含量的增加,断口由韧性沿晶断裂逐渐转变为脆性沿晶断裂和解理型穿晶断裂两种断裂方式的混合,并且随着氢含量增加,穿晶解理断裂特征增多。

Diffusion bonding test of hydrogenated porous Ti6AI4V alloy was carried out by using Gleeble1500 thermal simulator. The influence of hydrogen on the quality of diffusion bonding for porous Ti6Al4V samples have been analyzed. The bonding rate, microstructure, bending strength and fracture morphology of the samples bonded with different hydrogen content were examined By using of optical microscopy（OM）, scanning electron microscopy（SEM） and electronic universal testing machine, respectivly. It was shown that the interface bonding rate improved gradually with the increasing hydrogen content. After diffusion bonding, the microstructure with lower hydrogen content transformed into equiaxed α ＋ lamellar（α ＋β） microstructure, while the microstructure with higher hydrogen content transformed into lath α＋equiaxed（α＋β）. The bending strength of porous Ti6A14V increased with higher hydrogen content, which was related to the strengthening effect of hydrogen and hydrides. With higher residual hydrogen content, the fracture of porous Ti6A14V alloy gradually changed from ductile intercrystalline fracture into a mixture of Brittle intercrystalline fracture and transcrystalline cleavage fracture, with more feature of transcrystalline cleavage fracture appearing.