GB459848A - Improvements in heat resistant alloys - Google Patents

Abstract

Articles which in use are subjected to repeated high temperature heating and cooling are made from an alloy prepared by adding to a molten nickel-containing mass, prior to casting, one or more of the rare earth metals (including scandium, yttrium, hafnium, and thorium) in such a quantity that if there is any residue in the finished alloy, it does not exceed 0,5 per cent. For instance, electric resistance elements may be made from an 80-20 nickel-chromium alloy treated in this manner. Before the rare earth addition, the mass may be subjected to treatments for deoxidizing, desulphurizing, improving the forgeability, etc.; for instance, it may be treated with alkaline earth metals such as calcium, calcium silicide, a Group V element such as phosphorus, arsenic or antimony, selenium, sulphur, tellurium, manganese, magnesium, silicon, or boron. Carbon, copper, iron, phosphorus, and sulphur may be present as impurities and aluminium, cobalt, molybdenum, or tungsten may be used to modify the mechanical properties. The rare earth addition may consist wholly or mainly of cerium or lanthanum, or commercial cerium may be employed. The finished alloy may contain up to 0,25 per cent of carbon. According to the second Provisional Specification, zirconium and titanium may also be present. Specifications 311,799, [Class 82 (i)], and 396,514 are referred to.