Combinatorial Development of Multicomponent Invar Alloys Via Rapid Alloy Prototyping

To develop novel Invar alloys in the practically infinite compositional space of multicomponent alloys, rapid alloy prototyping is used to investigate five multicomponent Invar alloys with 5 at.% addition of Al, Cr, Cu, Mn and Si to a super Invar alloy (Fe 63 Ni 32 Co 5 ; at.%), respectively. All alloys show abnormally low thermal expansion coefficients below the Curie temperature and saturation magnetization deviating from the Slater-Pauling curve, revealing their Invar-behavior. The relationships among valence electron concentration, magnetic properties, and Invar behavior of the various multicomponent alloys are discussed. The Invar alloy with Cu addition is particularly promising, as it shows a 40 K larger temperature range (above room temperature) of low thermal expansion coefficient (<5.87×10 -6 K) and 2.8% higher hardness compared to the conventional super Invar alloy. The work thus also successfully demonstrates the capability of using rapid alloy prototyping for developing multicomponent multi-functional alloys.