ABSTRACT Recently, sintered‐Ag composites incorporating diverse second phases have been developed to inhibit Ag thermal coarsening. However, inconsistent microstructural evolution during thermal aging is observed among different additives, with some acting as effective barriers to coarsening while others showing negligible impact. Herein, submicron WC is selected as an additive to evaluate its long‐term effect on suppressing microstructural coarsening. The effects of WC addition on the Ag‐based sintered joints are investigated using Ag, Ag–2 wt%WC, and Ag–5 wt%WC systems during thermal aging at 250°C for 1000 h. Pure sintered Ag exhibits substantial microstructural coarsening accompanied by significant strength variation, with the apparent porosity varying between 24.8% and 39.7% during aging. In contrast, Ag–5 wt%WC demonstrates enhanced microstructural stability and strength retention while maintaining a nearly constant porosity between 27.0% and 28.6%. WC addition introduces a trade‐off between initial performance and long‐term reliability in Ag‐based sintered joints. Although the initial shear strength and thermal conductivity decrease, the improved resistance to thermal coarsening enables better strength retention during thermal aging. Combined with reported Ag–additive systems, the underlying coarsening‐resistance mechanism is discussed and primarily attributed to robust Ag–additive interfacial bonding, which provides effective grain‐boundary pinning against grain growth.
Liu et al. (Thu,) studied this question.
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