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

In this research, the influence of process parameters such as sintering temperature and current during alloying and densification of silicon-germanium (Si-80-Ge-20) powder mixture using spark plasma sintering (SPS) was reported. Si-80-Ge-20 powder mixture was consolidated at the temperature range 900-1200 degrees 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 Si-80-Ge-20 powder mixture. Transmission electron microscope (TEM) study was made on milled Si-80-Ge-20 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 Si-80-Ge-20 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(K-IC) values of 630 VHN and 2.19 MPa root m was achieved for SiGe alloy sintered at 1200 degrees C, respectively. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.