Densification and alloying of ball milled Silicon-Germanium powder mixture during spark plasma sintering

•Rapid alloying and densification of SiGe alloy by reaction synthesis using SPS.•SPS process parameters effect during reaction synthesis.•Synthesis of pure bulk nanostructured SiGe alloy of higher fracture toughness.•Simple and effective method for synthesis of pure SiGe alloy.

In this research, the influence of process parameters such as sintering temperature and current during alloying and densification of silicon-germanium (Si80-Ge20) powder mixture using spark plasma sintering (SPS) was reported. Si80-Ge20 powder mixture was consolidated at the temperature range 900-1200 °C with 40 MPa pressure for 5 min. soaking. X-ray diffraction (XRD) study was made on sintered compacts to confirm the Si(Ge) alloy formation. Scanning electron microscope (SEM) was used to understand the morphology, particle size and distribution of un-milled and milled Si80-Ge20 powder mixture. Transmission electron microscope (TEM) study was made on milled Si80-Ge20 powder mixture and bulk SiGe alloy to confirm the nano-crystallinity and alloy formation. Fracture toughness of sintered bulk SiGe alloy was determined from Palmqvist cracks geometry model using Vickers hardness testing. It is understood that, during spark plasma sintering nano-structured Si80-Ge20 powder simultaneously increases the densification and reaction kinetics. It helps to achieve homogenous nanostructured SiGe alloy of near theoretical density. The superior hardness and benchmarked fracture toughness (KIC) values of 630 VHN and 2.19 MPa√m was achieved for SiGe alloy sintered at 1200 °C, respectively.

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