Evaluation of embrittlement in isochronal aged Fe-Cr alloys by magnetic hysteresis loop technique

Abstract

Fe-Cr alloys with different Cr contents were prepared by an arc melting technique. The alloys were isochronally aged in the range from 400°C to 900°C with 50°C steps with a holding time of 100 hours. The ageing produced embrittlement in the alloys due to either the formation of a Cr-rich α' phase or a σ phase at high temperatures. Magnetic Hysteresis Loop (MHL) and Micro-Vickers hardness were measured at each step to correlate the magnetic and mechanical properties. Coercivity and hardness of the alloys were increased and remanence decreased up to 500-550°C due to formation of a Cr-rich α' phase. Beyond 500-550°C range, the coercivity and hardness decreased and remanence increased due to the coarsening or dissolution of the Cr-rich α' phase. In the Fe-48% Cr alloy, formation of the σ phase at 700°C reduced the maximum induction of the alloy significantly. © 2011 Journal of Magnetics.