Nonferromagnetic Elinvar-Type Alloys in the Mn–Ni–Mo System

Abstract

Measurements of Young’s modulus at −150∼400°C and of rigidity modulus, thermal expansion and hardness at room temperature have been carried out with Mn–Ni–Mo alloys subjected to cold working and heat treatment. The ternary alloys slowly cooled after annealing for 1 hr at 950°C show an anomalous temperature dependence to be associated with the antiferromagnetic\ ightleftarrowsparamagnetic transformation. Young’s modulus at room temperature do not show any significant variations in both the cold worked and annealed states, but this value tends to increase with increasing manganese or molybdenum concentration. The temperature coefficient of Young’s modulus show a wide variation from a negative to a positive value by annealing, water quenching, cold working, and reheating after water quenching or cold working, with a strong composition dependence. The variations in rigidity modulus and its temperature coefficient with heat treatment, cold reduction rate and composition are very similar to those in Young’s modulus and its temperature coefficient. The vickers hardness of the alloys varies in a complex manner between about 100 to 650 by the various treatments and compositions. The corrosion resistivity of Mn–Ni–Mo alloys is relatively good.