Title: Effect of nano-yttria dispersion on the microstructure and mechanical properties of W-Ni-Co alloys

Authors: C. Pandi Selva Durai; V. Arul Mozhi Selvan; T.K. Singha; S. Kumaran

Addresses: Department of Mechanical Engineering, National Institute of Technology, Tiruchirappalli, India ' Department of Mechanical Engineering, National Institute of Technology, Tiruchirappalli, India ' Heavy Alloy Penetrator Project, Tiruchirappalli, India ' Department of Metallurgical and Materials Engineering, National Institute of Technology, Tiruchirappalli, India

Abstract: The effect of nano-Y2O3 (0.25-0.75 wt.%) addition in tungsten heavy alloy which consists of 93 weight percentage tungsten and Ni/Co ratio fixed at 9 was investigated. Ni, Co and Y2O3 were mixed in high-energy ball milling to obtain nanostructure and this mixture subsequently blended with tungsten (W) in a low energy ball milling. The powder mixture was consolidated by cold-isostatic pressing, and the green compact was sintered at 1,475°C for 2 hrs, followed by post annealing at 1,100°C for 1.5 hrs. W-Ni-Co alloys thus processed exhibits density greater than 96% of theoretical density. Lowest distortion of 1.5 mm was found in yttrium oxide dispersed W-Ni-Co alloy using a coordinate measuring machine. The second phase of nano-Y2O3 distributes in W-grains and matrix significantly influences grain morphology, size, microstructural features and mechanical properties. Dispersion of nano-Y2O3 enhances hardness of the matrix due to the grain refinement and formation of the inter-metallic compound.

Keywords: cold-isostatic pressing; CIP; contiguity; high-energy ball milling; nano-Y2O3; W-Ni-Co heavy alloy.

DOI: 10.1504/IJMPT.2019.104553

International Journal of Materials and Product Technology, 2019 Vol.59 No.4, pp.291 - 302

Received: 06 Oct 2018
Accepted: 28 Jan 2019

Published online: 20 Jan 2020 *

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