Hakaru Masumoto1, Shôhachi Sawaya1 and Michio Kikuchi1
1The Foundation; The Research Institute of Electric and Magnetic Alloys, Sendai
Measurements of Young's modulus at -150°∼400°C and of thermal expansion, rigidity modulus and hardness at room temperature have been carried out with Mn-Cu-Fe alloys subjected to a variety of heat treatment and cold working. It is shown that when slowly cooled after heating at 900°C for 1 hr, Mn-Cu-Fe alloys containing 20.13 ∼ 55.00%Cu and 2.55 ∼ 30.25%Fe exhibit an abnormality on the Young's modulus vs temperature curves which correspond to antiferromagnetic Néel points. The values of Young's modulus at room temperature in the annealed state were higher than those in the cold worked or wate rquenched states, and the difference becomes greater with increasing manganese or iron content. The temperature coefficient of Young's modulus is remarkably varied by composition as well as by annealing, water quenching, cold working, and reheating after water quenching or cold working. The temperature coefficients of Young's modulus as a function of composition exhibit a large maximum and minimum in positive or negative sign, thus revealing the Elinvar property. The variations in rigidity modulus and its temperature coefficient with heat treatment, reduction rate and composition have a close resemblance to those in Young's modulus and its temperature coefficient. The hardness undergoes a complicate relation with composition, heat treatment and reduction of the alloys, the Vickers hardness being about 130 to 800. The oxidation-and corrosion-resistivities of the Mn-Cu-Fe alloys are fairly high.
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