Decomposition of the solid solution in commercial semiproducts from aluminum alloys

Abstract

Considerable progress has been made recently in the field of production and application of aluminum alloys with lithium. The accumulated actual material and its analysis has made it possible to use successfully an aluminum-lithium alloy 1420 for the production of welded power packs of aircraft. The established laws have been used in the industry for developing new technological processes and regimes tbr the production and heat treatment of stamped preforms from this alloy. It is often assumed that only A1 - Li alloys have some specific technological and service features though a careful analysis shows that traditional alloys without lithium possess them too in similar structural states. In the first place these features are the sensitivity to repeated (technological or solar) heating, the anisotropy of the specific elongation and the fracture resistance, and the susceptibility of delayed fracture. Until recently, some problems on the phase transformations in A1 - Li alloys that concern the segregation of the 13-phase in alloy 1420, the T-phase in alloy 1450, and the 5-phase in AI-Li alloys have remained a subject of discussion; the problems of the qualitative and quantitative variation of the phase composition upon heat treatment under actual industrial conditions require a more detailed discussion. In the present work we analyze the special features of the decomposition of the solid solution in industrial semiproducts from alloy D16 and in A1 - Li alloys.