Mn-Ni-Cr系非磁性エリンバ一型合金について

Abstract

Measurements of Young’s modulus at −150∼400°C and rigidity modulus, thermal expansion and hardness at room temperature have been carried out with Mn-Ni-Cr alloys subjected to a variety of heat treatment and cold working. It was found that in Young’s modulus vs temperature curves, the ternary alloys slow coold after heating for 1 hr at 950°C showed distinct anomalous changes related to their antiferromagnetic\ ightleftarrowsparamagnetic transformations. Young’s modulus at room temperature is higher in the state of annealing than in the cold working or water quenching state and the reheating state after cold working or water quenching, and the values tend to increase with increasing nickel and chromium contents. The temperature coefficient of Young’s modulus shows a wide variation with annealing, water quenching, cold working, and reheating after water quenching or cold working, and also with alloy composition. The temperature coefficients of Young’s modulus as a function of composition exhibit a large positive maximum, thus showing the Elinvar property. The variation in rigidity modulus and its temperature coefficient with the process of heat treatment, cold reduction rate and composition shows a close similarity to that in Young’s modulus and its temperature coefficient. The hardness shows a very complicated change with the process of heat treatment, cold reduction rate and alloy composition, showing the Vickers hardness of about 100 to 550. Further, the corrosion resistance of Mn-Ni-Cr alloys is fairly large.