Microstructure and densification of gas atomised Fe–Cr–B based alloy powder consolidated by spark plasma sintering

Abstract

This paper is a study of microstructure and densification of a gas atomised Fe–45Cr–5.9B–2Si–0.1C (wt-%) alloy powder consolidated using the spark plasma sintering (SPS) process. The results showed that the fabricated alloy contained about 65 wt-%(Cr,Fe)₂B plates and 1 wt-%(Cr,Fe)₇C₃ precipitates dispersed in a 34 wt-% body centred cubic Fe based solid solution matrix containing Cr and Si. The powder was fully densified with solid state sintering for a short period of time (<10 min). After sintering, the phases did not transform, and the fraction, shape and aspect ratio of (Cr,Fe)₂B did not change. In addition, we adapted the known SPS constitutive densification model from Olevsky and Froyen to include a microstructure factor describing deformation of a metal matrix composite powder. The model was in reasonable agreement with the experimental results.

Keywords:

• Fe–Cr–B alloy
• Metal matrix composite
• SPS
• Electron microscopy
• Densification modelling

Acknowledgements

The authors would like to thank Liquid Metal (CA, USA) for the powder provided, Sente Software Ltd (UK) for the high temperature strength calculations and Netzsch Instruments North America (LLC applications laboratory, Burlington, MA, USA) for the DSC testing. The authors are grateful to King Fahd University of Petroleum and Minerals (KFUPM, Dhahran, Saudi Arabia) for the scholarship awarded to Ahmad A. Sorour.