Mechanical and magnetic properties of alloys near the concentration range of the existence of Co3(Al,W) intermetallic compound

Abstract

An experimental study of the mechanical and magnetic properties of Co–8 at % Al–X at % W (where Х = 4.6; 6.8; 8.5; 10; 12) polycrystalline alloys has been carried out depending on the tungsten content. It has been shown that an increase in the tungsten content induces the following changes: Young’s modulus changes from 240 to 259 GPa and the microhardness HV changes from 290 to 413 MPa. The Curie temperature of the intermetallic γ' phase (L12) grows from 1025 to 1049 K, and the saturation magnetization of the alloys decreases. The value of the coercive force also increases, from 1 to 500 Oe. The calculations of the specific heat of the γ' (L12)–γ (dcc) phase transition has shown that the highest amount of heat (304 J/g) is absorbed upon the phase transition in the sample containing the largest amount of tungsten (12.6 at %). The results obtained indicate the diffusion character of the transition, the rate of which is controlled by the diffusion of the slowest component of the alloy (in this case, tungsten). It has been found that the solvus temperature of the γ' phase increases from 1009 to 1044°С with an increase in the tungsten content from 4.6 to 12.6 at %.