Phase, microstructure and properties evolution of fine-grained W-Mo-Ni-Fe alloy during spark plasma sintering

Fine-grained tungsten (W) heavy alloy containing molybdenum (Mo) with W particle sizes of less than 5 mu m were fabricated by spark plasma sintering (SPS) pre-milling W-2Mo-7Ni-3Fe powder at a lower temperature of 1000-1250 degrees C. Phase, microstructure and mechanical properties evolution of W-Mo-Ni-Fe alloy during spark plasma sintering were studied in detail. As increasing sintering temperature, the hardness of the alloy decreased rapidly. However, bending strength of the alloy demonstrated a fall-rise-fall trend, and the maximum strength was obtained at 1150 degrees C. The W-2Mo-7Ni-3Fe alloy microstructure was composed of white W-grain, gray W-rich structure, black gamma-(Ni, Fe, W, Mo) binding phase, and deep-gray W-rich structure. The intergranular fracture along the W/W grain boundary is the main fracture modes of W-2Mo-7Ni-3Fe alloy. (C) 2011 Elsevier Ltd. All rights reserved.