Vacuum diffusion bonding of TiB2 cermet to TiAl based alloys

Abstract

Vacuum diffusion bonding of TiB₂ cermet to TiAl based alloys was carried out at 1123 – 1323 K for 0.6 – 3.6 ks under 80 MPa. The microstructural analyses indicate that a compound Ti(Cu, Al)₂ is formed in the interface of the TiB₂ /TiAl joints, and the width and quantity of the Ti(Cu, Al)₂ compound increase with the increase of the bonding temperature and bonding time. The experimental results show that the shear strength of the diffusion bonded TiB₂ /TiAl joint is 103 MPa, when TiB₂ cermet is bonded to TiAl based alloy at 1223 K for 1.8 ks under 80 MPa.     

TiAl/40Cr钢扩散连接界面组织结构对接头强度的影响

扩散连接界面组织结构是影响连接性能的关键因素，不同的界面组织结构及生成相所决定的接合强度不同．本文研究了TiAl/40Cr钢的扩散连接，结果显示：连接温度过高及连接时间过长时，由于界面处形成了过多的TiC脆性层及Ti3Al FeAl FeAl2的金属间化合物混合层，接头拉伸强度低；当连接温度较低及连接时间较短时，界面紧密接触与元素扩散不充分，接头拉伸强度也较低．脆性TiC层的生成导致TiAl与40Cr钢之间的扩散连接性能较差，接头均破断于TiC层或TiC层与Ti3Al FeAl FeAl2的金属间化合物混合层之间．     

Transient liquid phase bonding of Gamma Met PX: microstructure and mechanical properties

Abstract

An investigation of microstructural development and structure–property relationships of transient liquid phase (TLP) bonded current generation γ-TiAl alloy, known as Gamma Met PX, is presented. This joining technique employed a composite interlayer consisting of a non-melting constituent (TiAl alloy) and a liquid forming constituent (copper). The microstructures of the bonds, identified using light microscopy and scanning electron microscopy, are correlated with room temperature mechanical performance. These studies suggested that joints can retain properties similar (i.e. >90%) to that of the bulk material when employing a suitable composite interlayer, bonding conditions and post-bond heat treatment. Additionally, comparisons are drawn between wide gap TLP bonding of an earlier generation γ-TiAl alloy, Ti–48Al–2Cr–2Nb (at.-%), and wide gap TLP bonding of Gamma Met PX.     

Technology and interface structure for diffusion bonding of Fe3Al/18-8 dissimilar materials

Abstract

The effects of technological parameters on the interface morphology and shear strength of Fe₃Al/18-8 diffusion bonded joints have been researched by means of a JXA-80 scanning electron microscope (SEM) and a digital tensile press test machine. Microstructural characteristics and fracture morphology near the Fe₃Al/18-8 diffusion interface, obtained under conditions of various technological parameters, have been analysed using the SEM. The test results indicate that a diffusion bonded joint with higher shear strength (σ_τ = 226 MPa) may be obtained with a heating temperature T = 1020 – 1040°C, holding time t = 45 – 60 min and pressure P = 12 – 15 MPa.     

TiAl/40Cr扩散焊未焊合、弱接合和微孔缺陷的智能识别

为了解决异种材料扩散焊质量超声波检测时,从回波幅度无法判断界面是否存在微小缺陷的问题,采用支持向量机技术构建了扩散焊界面缺陷识别模型.以TiAl和40Cr扩散焊接头为研究对象,采用超声波水浸聚焦法采集扩散焊界面信号,从信号中提取4个特征值,优化样本数量和核参数后,训练扩散焊界面缺陷识别模型.扩散焊试样界面信号经模型识别后,根据C扫描图像的位置重构识别图像.结果表明,该模型有效地识别出未焊合、弱接合和微孔缺陷,3种缺陷的正确识别率分别为93%、90.5%和91.5%,识别图像直观地显示了界面的缺陷.TiAl/40Cr扩散焊界面缺陷识别模型实现了扩散焊试样界面缺陷的智能识别.