An analysis of deformation mechanism in the Si_3N_4-AgCuTi + SiCp-Si_3N_4 joints by digital image correlation

摘要

The composite filler shows more advantages than traditional brazing alloys, and has been widely introduced into joining ceramics or ceramics to metals. However, the underlying formation and strengthening mechanisms remained uncertain in the joint. In current research, SiCp (p = particle) was incorporated in Ag-Cu-Ti brazing alloy for joining Si_3N_4 ceramic. Nanoindentation method was introduced for probing the mechanical properties of reaction phases between the brazing alloy and SiCp. A novel formation mechanism model was thus proposed. In addition, optical microscope (OM) in conjunction with digital image correlation (DIC) techniques has been first applied to elucidate the deformation mechanism in the joint with and without SiC incorporation. The following reasons were believed to strengthen the brazed joint: load-transfer ability of SiCp, plastic relaxation in the brazing layer and CTE reduction of the composite filler.