Optimization of Thermoelectric Properties in TiNiSn Half-Heusler Alloy by Controlling Microwave Sintering Time Using Microwave Synthesis-Cold Pressing-Microwave Sintering Method

Abstract

Homogeneous pure TiNiSn Half-Heusler (HH) alloys were successfully prepared in a time-efficient manner using microwave synthesis-cold pressing-microwave sintering (MCM) process in this study. The effects of different microwave sintering time on the composition, microstructure and thermoelectric properties of TiNiSn materials were studied. When the time of microwave sintering was 6 min, the TiNiSn sample was almost pure phase except for a small amount of TiNi2Sn phase. More TiNi2Sn impurity can be found in the TiNiSn sample after microwave sintering of 10 min due to the decomposition of TiNiSn resulting from the over-sintering. The thermoelectric properties of TiNiSn samples prepared by MCM process could be effectively improved by adjusting appropriate sintering time. The TiNiSn alloys sintered for 6 min had the zTmax value of 0.15 at 800 K.