铝基复合材料的活性液相扩散焊新工艺

为优化中间层合金系的设计,对液相扩散焊过程中陶瓷颗粒/金属(P/M)界面的弱化、强化及断裂模式进行了研究,发现在采用纯Cu箔的Al_2O_3p/Al复合材料液相扩散焊件的剪切断口上,Al_2O_3颗粒未破裂,断口上所有Al_2O_3颗粒及部分金属表面光滑,无粘结物生成,表明P/M界面结合弱而呈"界面脱粘"断裂方式.为此,提出了一种旨在改善P/M弱界面润湿性的新工艺--活性液相扩散焊,要求所用中间层内必须同时含有降熔元素及可与陶瓷增强相反应的活性元素(Ti).当Ti含量较低时,Al_2O_3颗粒增强相表面上出现细微、凹凸不平且不连续的界面粘结物(反应物);当Ti含量较高时,P/M界面可形成强力结合,剪切测试中足以使一些陶瓷颗粒本身破裂.

Novel Process of Active-Transient Liquid Phase (A-TLP) Bonding for Aluminum Matrix Composite

The weakening, enhancement and fracture mode of the interface between ceramic par-ticulate reinforcement and metal (P/M) in transient liquid phase(TLP) bonded joint of aluminum matrix composite are investigated to optimize the design of alloying system of interlayer. From the fracture surface of the TLP bonded joint of Al_2O_3p/Al using pure copper foil, it can be seen that the Al_2O_3 particulates exhibit smooth surface without adhesives or disruption, and some are-as of metal on fracture surface also appear smooth. The results indicate that the P/M interface bonding gets weak showing interfacial debonding fracture mode. A novel process of active-transi-ent liquid phase (A-TLP) bonding with an interlayer containing both melting point depressant (MPD) and active alloying element is hence proposed to improve the interracial wettability be-tween weak P/M interface. When the Ti content is lower, a large amount of discontinuous adhe-sives with small size are present on the Al_2O_3 particulate surfaces in the A-TLP bonded joint as a result of reaction, while the P/M interracial bonding becomes so strong that many Al_2O_3 particu-lates are disrupted during shear test in the case of higher Ti content.