Antiferromagnetic Elinvar-Type Alloys in the Mn–Cu–W System

Abstract

The Young’s modulus at −150∼400°C and the elastic modulus, thermal expansion and hardness at room temperature have been measured for Mn–Cu–W alloys subjected to cold working and various heat treatments. It is shown that an anomaly associated with the antiferromagnetic\ ightleftarrowsparamagnetic transformation appears on the Young’s modulus vs temperature curves of the ternary alloys slow-cooled after heating at 900°C for 1 hr. The Young’s modulus at room temperature is at a little variance between the states of annealing, cold working and water quenching, but its value has a tendency to increase with increase in Mn or W content. The temperature coefficient of Young’s modulus differs greatly by the processes of annealing, cold working, water quenching and reheating after cold working or water quenching; the value undergoes a remarkable variation with composition, also. The presence of a large positive maximum on each of the temperature coefficient of Young’s modulus vs composition curves indicates the Elinvar characteristics of the ternary alloys. The rigidity modulus and its temperature coefficient at room temperature show a very similar variation to that of Young’s modulus and its temperature coefficient for the composition, heat treatment and cold working. In general the hardness of the ternary alloys undergoes a complicated variation within the range of 100∼660 by cold working, water quenching and heat treatment after cold working or water quenching as well as with composition. The corrosion resistivity is fairly good.