Effects of sintering temperature and time on defect evolution and compression properties of Ti-Al₃Ti laminated composites

For metal-intermetallic laminated composites, various types of defects often occur during the preparation process. This paper studied the evolution and formation mechanism of defects, such as pores, tunnel cracks, and delamination cracks in Ti-Al₃Ti laminated composites prepared by vacuum hot-pressing method. Moreover, quasi-static and dynamic compression tests were performed to study the effects of pores and delamination cracks on the compression properties of the composites. The results showed that for Ti-Al₃Ti laminated composites prepared at 710 ℃, their Al₃Ti layers exhibit a porous structure, and the porosity of Al₃Ti layers firstly decreases and then increases under the combined action of press, the self-propagating reaction and Al₃Ti grain coarsening. The tunnel cracks in Ti-Al₃Ti laminated composites are resulted by tensile residual stresses and the inherent brittleness of Al₃Ti. For Ti-Al₃Ti laminated composites prepared at 680 ℃, the formation of delamination cracks is mainly related to the diffuse reaction of Ti/Al atoms and the Kirkendall effect, and the numbers of delamination cracks increase with the increasing of sintering time. Moreover, the pores and delamination cracks greatly deteriorate the compression properties of Ti-Al₃Ti laminated composites. Crack-free and dense Ti-Al₃Ti laminated composites exhibit the highest compression properties.