Influence of Fe on martensitic and magnetic transformation of p based Co-Ni-Al alloy

The effects of Fe element on the martensitic and magnetic transformation of Co₃₈Ni₃₃Al₂₉ and Co_72-xNi_xAl₂₈ alloys were investigated by optical micrography, DSC and VSM methods. It is found that Curie point increased 15 K by 2% Fe element for Co_38-xNi₃₃Al₂₉Fe_x alloy quenched from 1623 K × 2 h, but when Fe element content reached 8%, its Curie point increased 160 K. Substituted 2% Fe element for Co element in Co_72-xNi_xAl₂₈ alloys, their Curie points increased 20-30 K and martensitic phase transition temperature decreased 150-170 K when quenched from 1623 K/2 h, whereas, their Curie points increased 30-70 K and martensitic phase transition temperature decreased 50-130 K when quenched from 1523 K/2 h. For the reason of increasing Curie point and decreasing martensitic transition temperature, substituting Fe for Co in β based Co-Ni-Al alloy enlarge the chemical composition range of Co-Ni-Al-Fe alloys located in T_c > T_m, made it move to Ni-rich and Co-poor, Al-poor angles. The variants of martensitic transition temperature and Curie point were discussed by average s + d-electron concentration (e/a).