Non-magnetic aluminium-lithium-magnesium alloy - which is hardened, and heat treated to contain Guinier-Preston zones

摘要

The alloy comprises 2-4.5% Mg, 1-1.2% Li or 7-8% Zn in stoichiometric proportions, balance Al. The alloy may contain a small amt. of Mn and Cr, or total max. 0.1%. After casting, homogenising, and working, the alloy is hardened by a water quench from 480 degrees C and subjected to a final heat treatment so that Guinier-Preston zones are formed, pref. heated for 12h to 120 degrees C with holding times of 30-60 min, depending on the dimensions of the workpiece. The magnetic susceptibility of the alloy is only about one half of 3/10th of that of known Al alloys. The prodn. costs of the alloy, which has only a slightly higher magnetic susceptibility than that of a Be bronze, are 5-10 fold lower than those for Be bronzes. It has a better corrosion resistance than known Al alloys.