Wetting and pressureless infiltration of Cu-xTi/SiC system at 1373 K

Abstract

In order to clarify more clearly the action mechanism of Ti at the interface between Cu–Ti alloy and SiC during wetting, the monocrystal, polycrystalline, and porous α-SiC substrates were selected for study by modified sessile drop method under high vacuum at 1373 K. The results show that there is no significant difference in wettability and spreading dynamics between monocrystal and polycrystalline α-SiC substrates. The critical titanium concentration causing wettability transformation is between 5 wt% and 7.5 wt%. The transformation of wettability mainly depends on the precipitation of continuous Ti3SiC2 layer with metalloid properties. Multilayer precipitation layers were observed in the interface structure, corresponding to three spreading stages: rapid spreading stage, which may be caused by TiC precipitation; At the stage of spreading stagnation, the corresponding interface failed to produce enough TiC; Slowly spreading to the equilibrium stage corresponds to the precipitation of Ti3SiC2. Cu-xTi on porous-SiC substrate failed to achieve complete pressureless infiltration during wetting, mainly because the volume of SiC and TiC consumed by the reaction is much smaller than the volume of the precipitated phase Ti3SiC2, which closed the pores and hindered the infiltration process. The results can provide theoretical basis for regulating the wettability, optimizing the interface structure between titanium-containing active alloys and carbide ceramics.