The metallurgy of remendur: Effects of processing variations

A recent development effort in telecommunications switching apparatus has been directed toward the production of a remanent reed, dry, sealed contact (remreed). Remendur, a medium-hard magnetic alloy nominally composed of equal parts iron and cobalt and 2.7-wt. percent vanadium, was chosen as the reed material in this contact. However, the application required the alloy to possess rather specific magnetic and mechanical properties and considerable difficulty was experienced in consistently processing Remendur into wire with these specified properties. To ascertain the sensitivity of these properties to variations in processing times and temperatures, and vanadium content, two melts of Remendur (2.5-percent V and 3.0-percent V) were processed with selected alterations in annealing temperatures at several stages. Microstructures were characterized following each step by light microscopy and were correlated with the appropriate ternary equilibrium diagram. Results demonstrate that microstructures developed by anneals between 900°C and 950°C are extremely sensitive to the precise temperature of the anneal and composition of the alloy. The microstructure, which strongly influences magnetic and mechanical properties, can be varied over the limits of the two-phase α 1 + γ region by variations in vanadium content of only 0.5 wt. percent and by the small 50°C temperature range.