Cf/Al composites and TiAl alloys were joined by laser ignited self-propagating high-temperature synthesis（SHS） with Ni-Al-Ti interlayer. The effect of Ti-Al content on interfacial microstructure and mechanical properties of the joints was investigated. Localized melt of the substrates occurred in the joints. γ-Ni0.35Al0.30Ti0.35, NiA l3 and Ni2Al3 reaction layers formed adjacent to the substrates. Joint flaws, such as pores and cracks, made the joint density decrease and worked as the fracture source, which led to the sharp decline of joint strength. Additive Ti-Al increased joint density and strengthened the interlayer adhesion to Cf/Al. The joint flaws could be controlled by changing the Ti-Al content. When the Ti-Al content was 0.1, the joint was free of cracks with high density and reached the maximum shear strength of 24.12 MPa.
The aim of this study was to develop a high-efficiency joining method of Cf/Al composites and TiA l alloys under the heat effect of laser-ignited self-propagating high-temperature synthesis（SHS）. The SHS reaction of Ni–Al–Zr interlayer was induced by laser beam and acted as local high-temperature heat source during the joining. Sound joint was obtained and verified the feasibility of this joining method. Effect of filler metals on the joint microstructure and shear strength was evaluated. When the joining pressure was 2 MPa with additive filler metals, joint shear strength reached the maximum of 41.01 MPa.
Cf/Al composites and TiAl alloy were joined by combustion synthesis in different joining conditions. Effects of additive Cu, joining temperature and holding time on joint microstructure and shear strength were characterized by employing DTA, SEM, EDS, XRD and shear test. Results show that the additive Cu in the Ti-Al-C interlayer could significantly decrease the reaction temperature owing to the emergence of Al--Cu eutectic liquid. Reaction degree of the interlayer was influenced by joining temperature and holding time. Due to the barrier action of formed TiAl3 layer, reaction rate of Ti and Al was determined by the atoms diffusion. The reaction between Ti and AI was more sensitive to the joining temperature rather the holding time. The joints shear strength was influenced by joining condition directly. The maximum shear strength of CS joints was 25.89 MPa at 600 ℃ for 30 rain under 5 MPa. Interface evolution mechanism of the CS joint was analyzed based on the experimental results and phase diagram.
In this study, Cf/Al composites and TiAl alloys were joined by a new method named laser-ignited selfpropagating synthesis（SHS）. Mixed powders of 63.0Ni-31.9Al-5.1Ti（wt%） were used as joining interlayer.Perfect joint was got. The microstructure evolution and formation mechanism of the SHS joint were investigated by scanning electron microscopy（SEM）, energy-dispersive spectroscopy（EDS） and X-ray diffraction（XRD）. Results show that localized melting occurs on both sides. One γ-Ni（0.35）Al（0.30）Ti（0.35） and two Ni-Al reaction layers form,respectively, in the TiAl/interlayer and Cf/Al/interlayer interfaces. The combustion of Ni-Al-Ti interlayer begins with the sharp reaction of Ni and Al. The interlayer product is a eutectic organization of NiAl and Al-rich γ.
采用BNi2钎料,对ZrB2-SiC陶瓷复合材料进行真空钎焊研究.借助SEM,EDS,XRD等分析测试手段分析了界面组织结构及性能.确定了最佳钎焊工艺参数:钎焊温度1160℃,保温时间20 min.结果表明,接头界面产物主要有δ-Ni2Si,β1-Ni3Si,ZrB2+C,Ni(s,s),Cr x B y C z.随着钎焊温度升高以及保温时间的延长,接头抗剪强度均先升高后降低.钎焊温度1 160℃,保温时间20 min,钎焊接头室温抗剪强度达到最大121.3 MPa.钎焊温度和保温时间对接头断裂方式的影响有相似的规律,在保温时间较短时,裂纹主要产生于钎缝中的Ni(s,s)中,之后向Ni元素扩散层中扩展;当保温时间适中时,断裂主要发生在Ni元素扩散层中;当保温时间延长时,裂纹主要产生于含有一定β1-Ni3Si相的Ni(s,s)中,之后向Ni元素扩散层中扩展.
In this study, it was reported a novel approach for joining Cf/A1 composites and TiA1 intermetallic by self- propagating high-temperature synthesis （SHS）. Mixed powders of 14A1-2Ni-3CuO were used as the SHS inter- layer, and differential thermal analysis test of A1-Ni-CuO interlayer was conducted to analyze the exothermic char- acteristic. Sound joint was got by SHS joining under the conditions of 600 ℃, 30 min, and 5 MPa. The joint was characterized by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, and X-ray diffrac- tion （XRD）. TiA13 and NiA13 are, respectively, formed in the TiA1/interlayer and Cf/A1/interlayer interfaces. Reac- tion products of Ni2Al3, NiAl3, A1203, and Cu were observed in the interlayer. And the formation mechanism of SHS joining was investigated.
