Abstract
Measurements of Young’s modulus at −150∼400°C and of rigidity modulus and hardness at room temperature have been performed for Mn–Cu–Fe alloys subjected to a varying set of heat treatment and cold working. A distinct knee which may be related to the paramagnetic \
ightleftarrows antiferromagnetic transformation can be seen in each Young’s modulus vs temperature curve for the compositions of 20.13∼55.00% copper and 2.55∼30.25% iron when slowly cooled after heating at 900°C for 1 hr. Room-temperature values of Young’s modulus in the state of annealing are higher than those in the state of cold working or water quenching, and the difference between the above states becomes prominent as the manganese or the iron content is increased. The temperature coefficient of Young’s modulus is remarkably changed by alloy composition and also by annealing, cold working, water quenching and reheating after cold working or water quenching. Large positive maxima which are observed in the temperature coefficient of Young’s modulus vs temperature curves indicate the Elinvar property of these alloys. Room-temperature values of rigidity modulus and its temperature coefficient show variations smilar to those of Young’s modulus and its temperature coefficient with methods of heat treatment, reduction rate and composition. The hardness undergoes a very complicated variation with composition, reduction rate, and methods of heat treatment, ranging in Vickers hardness from approximately 130 to 800. Both corrosion and oxidation resistivities of the ternary alloys are very high.
