The Magnetic Properties of Ordered Nickel-Manganese Alloys

Nickel-manganese alloys containing 20.1 percent, 21.4 percent, and 25.3 percent Mn in the form of Rowland rings were put into an ordered condition by very slow cooling to 380°C, and long annealing at that temperature. Magnetization curves and hysteresis loops at room temperature showed that the 21.4 percent Mn alloy was very soft magnetically, while the 25.3 percent Mn alloy was relatively hard magnetically. The 20.1 percent Mn alloy was magnetically soft, but not so soft as the 21.4 percent alloy. The magnetic properties of the ordered 21.4 percent Mn alloy changed markedly from room temperature to about 120°C. Induction at 30 oersteds decreases very rapidly, and the maximum permeability goes through a sharp maximum at 91°C. Coercive force and remanence also decrease during the same temperature interval.