Abstract
The thermal expansion, magnetic properties, lattice constants, hardness and workability were measured for Mn-Ge based ternary alloys cooled at various rates after homogenizing at 1100 K for 10.8 ks.
In the thermal expansion curves of Mn-20 and 22%Ge based ternary alloys containing Co or Ni less than 5% and 10%Fe, the Néel temperature of the ε-phase clearly appeared, showing the Invar characteristic below the temperature. The zero region of the thermal expansion coefficient at room temperature is widened by Fe addition, while it is narrowed by Ni or Co addition.
The temperature dependence of the magnetization of the ternary alloys shows almost the same behaviour as that of binary alloys. The ε-phase showing the antiferromagnetism at room temperature is stable for the addition of the third elements.
The vickers hardness of Mn-20%Ge-Fe alloys is lowered about 100 from the value of 500 of binary alloys by some Fe addition, keeping a constant value of 400 up to 10%Fe.
The machinability and forgeability of the ternary alloys in the ε-phase are better than those of the binary alloys.
