Microstructure and Hardness Property of Internally Oxided AgCdO Alloy

Microstructure and hardness property of AgCd alloy internally oxided at 973K for 1 h - 24 h with O2 atmosphere of 3 atm was investigated. Band typed CdO phase was formed at grain boundaries, and particle typed CdO phase was formed at grain interior. In this alloy, it was found that oxygen adsorpted at surface diffuses to interior through grain boundaries, and it subsequently diffuses into grain interior during internal oxidation. No Ag exduation was found in this alloy. The thickness of oxidized layer increased with increasing holding time at given temperature. Hardness of the oxidation zone was 125 ± 5 Hv, which value is higher two times than that of the oxidation free zone. The higher hardness of oxided region than the oxidation free zone was attributed to the dispersion strengthening by CdO particles.