Thermal Stability and Mechanical Properties of Thermoelectric Tetrahedrite Cu12Sb4S13

Tetrahedrite Cu12Sb4S13 was prepared by mechanical alloying and hot pressing, and its thermal stability and mechanical properties were examined. The phase transformation (decomposition), chemical composition, elemental redistribution, microstructure, hardness, and three-point bending strength were studied under various aging conditions (atmospheric, temperature, and time). Endothermic peaks were observed at temperatures from 845K to 892K and were found to be related to tetrahedrite decompositions. The Vickers hardness of the pristine specimen was 2.2 GPa on average, and did not significantly change with the aging conditions. The bending strength of the pristine specimen was 26.7MPa on average, and it remarkably decreased to 6.2MPa after aging at 723K for 100h in air. However, it was 21.4MPa after aging at 723K for 100h in vacuum.