Analyses of the spreading kinetics of AgCuTi melts on silicon carbide below 900 °C, using a large-chamber SEM

• Spreading of AgCuTi drops on SiC was observed using a large-chamber SEM.
• The measured spreading rate was correlated with models for reactive spreading.
• A transition between the spreading limiting mechanisms is proposed.
• Triple line distortions were observed during cooling.

Studies of the spreading kinetics of molten metals on ceramic substrates provide valuable information about the processes determining the interaction between these two materials. Based on experimental and theoretical works, two determining wetting types have been proposed for a variety of high-temperature systems – the reaction limited wetting and the diffusion-limited wetting. In the scope of this contribution an AgCuTi–SiC-system is investigated, which, despite of its high relevance for joining applications, has not yet gained much attention in fundamental works.The experiments were carried out on a heating stage placed in a large-chamber SEM. This novel method, allows high-resolution imaging and a precise observation of the changes of the liquid drop. Images taken every 5 s were used to measure the wetted surface as a function of time at temperatures between 830 and 890 °C.The AgCuTi-melt exhibits different spreading stages during the wetting process. It was shown that, at the beginning of the wetting, the spreading kinetics is determined by the reaction rate at the triple line. After reaching a distinct temperature-dependent angle, the titanium diffusion becomes the main limiting factor.

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