ALUMINUM-BASE ALLOY AND METHOD OF ITS HEAT TREATMENT Russian patent published in 1999 - IPC

FIELD: aluminum-base alloys, mainly, of the AlLi system designed for application in capacity of structural material in aerospace engineering and methods of their heat treatment. SUBSTANCE: alloy has the following chemical composition, mas.%: lithium, 1.5-1.9; magnesium, 4.1-6.0; zinc, 0.1-1.5; at least one element from the group including beryllium, 0.001-0.2; yttrium, 0.1-0.5; zirconium, 0.05-0.3; scandium, 0.01-0.3; aluminum, the balance. The alloy is treated as follows: hardening from temperature of 400-500 C in cold water or in the air; straightening by tensioning with deformation degree of not more than 2%; stage ageing: the 1st stage, at 80-90 C, for 3-12 h; the 2nd stage, at 110-125 C, for 5-12 h with subsequent cooling at the rate of 2-8 C/h for 10-30 h. EFFECT: improved thermal stability of alloy properties and weldability with strength high enough for manufacture of facing materials. 3 tbl