Preparation of Cu ₂ Se Thermoelectric Materials via Mechanical Alloying and Hot‐Press Sintering

ABSTRACT

Cu ₂ Se thermoelectric materials were prepared by mechanical alloying (MA) followed by hot press sintering (HPS). An orthogonal design was utilized to examine the influences of ball milling duration, rotational velocity, and ball‐to‐powder proportion on the powder phase configuration and morphology during the alloying procedure. Furthermore, the modulating impact of Ni doping on the thermoelectric characteristics of the material was investigated. X‐ray diffractometer (XRD), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS) were employed to investigate the phase composition, surface and cross‐sectional morphology, micro‐area elemental content and distribution of Cu ₂ Se. The Seebeck coefficient and resistivity of Cu ₂ Se were measured using a Seebeck coefficient/resistance analysis system LSR‐3, and the thermoelectric properties were tested using a laser thermal conductivity meter. The results demonstrated that Cu ₂ Se powder can be successfully synthesized via this method. Among the processing parameters, the ball‐to‐powder ratio had the greatest impact on grain size, with the optimal grain size corresponding to process parameters of 350 r/min, ball‐to‐powder ratio of 20:1, and ball milling for 10 h. Under the conditions of 450 r/min, ball‐to‐powder ratio of 15:1, and ball milling for 10 h, the ZT value of Cu ₂ Se reached 0.236 at 750 K. Ni doping could effectively reduce thermal conductivity reaching 0.838 W·m ⁻¹ ·K ⁻¹ at 970 K, but the electrical properties decreased, with a ZT value of 0.227.