GB430987A - Improvements in the manufacture of magnetic alloys - Google Patents

Abstract

In the manufacture of magnetic nickel-iron alloys containing 30-90 per cent of nickel to which has been added at least one element of low solid solubility, e.g. silver, beryllium, antimony, magnesium, calcium and copper, the alloys are annealed at a temperature of 900 DEG C., or over to form a homogeneous solid solution, cooled from that temperature sufficiently rapidly to obtain a state of super-saturation of the added element or elements in solid solution, subjected to an amount of cold working sufficient to reduce them to their final size, e.g. a reduction of thickness of from 10-90 per cent, and then soaking the alloys at p a temperature in excess of 250 DEG C., but below 500 DEG C., for a period of time sufficient to produce a precipitation of some of the added element or elements. One or more freely soluble resistance elements such as chromium, molybdenum, manganese, tungsten, aluminium, silicon, vanadium and cobalt may be added to the alloys. Copper may act as a precipitating element or as a freely soluble element especially when one of the other freely soluble elements is present; the capacity of the solute for the copper decreasing in proportion to the amount of iron present and also to the presence of the freely soluble elements. In an example, 98,5 parts of an alloy containing 40 parts of nickel, 60 of iron, 0,5 of manganese and 1,5 of chromium was melted with 1,5 parts of silver and the alloy cast. The casting was hot forged, annealed at 1100 DEG C., for 30 minutes, cold rolled without intermediate annealings down to 0,01 inch strips and sheared. The cold rolled strip was then soaked for 2 hours at 300 DEG C. Specifications 357,947 and 386,682 are referred to.