On the Nonferromagnetic Elinvar-Type Alloys in the Mn-Ni-W and Mn-Ni-W-Mo Systems

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-W and Mn-Ni-W-Mo alloys subjected to various heat treatments and cold working. Young’s modulus vs temperature curves of the ternary and quarternary alloys slowly cooled after heating for 1 hr at 950°C showed distinct anomalous changes associated with antiferromagnetic\ ightleftarrowsparamagnetic transformation. Young’s modulus at room temperature does not show any great difference by the states of cold working and heat treatment, but it tends to increase with increasing manganese, tungsten or molybdenum content. The temperature coefficient of Young’s modulus is greatly affected not only by annealing, water quenching, cold working and reheating after water quenching or cold working but also by alloy composition. The positive temperature coefficient of Young’s modulus exist in a wide composition range, showing the appearance of the Elinvar property. The variation of rigidity modulus and its temperature coefficient with heat treatment, cold reduction rate and composition is quite similar to that of Young’s modulus and its temperature coefficient. The hardness shows a very complicatd change about 100 to 600 within the range of in Vickers hardness by the aforementioned treatments. The ternary and quarternary alloys have fairly good corrosion resistivity.