Effect of carbon dilution on the low temperature thermal and magnetic properties of f.c.c. nickel base alloys

Abstract

The low temperature specific heat of ternary dilute alloys of carbon with f.c.c. binary nickel-cobalt and nickel-iron matrices have been measured between 1.2 and 8K. The results have been compared with former experiments on the parent alloys without carbon. The electronic specific heat coefficient is in the case of nickel increased by 35 mJK^-2 mol^-1 unit atomic carbon concentration. When iron or cobalt is added to the matrix, the effect of carbon rapidly decreases. This behaviour is attributed to the erasing of the van Hove peak at the top of the band of nickel, by addition of iron or cobalt. When the iron content reaches the border value between strong and weak ferromagnetism ( approximately=50%) the gamma increment per unit carbon concentration changes from weakly positive to strongly negative values, the increment of magnetization per metal atom changes from negative (-3 mu _B per carbon atom) to strongly positive.