INVESTIGATION OF THE INFLUENCE OF HEAT TREATMENT MODES ON THE STRUCTURE AND PROPERTIES OF SHEETS OF ALUMINUM-LITHIUM ALLOY V-1469
The effect of heat treatment regimes for sheets 2 mm thick of aluminum-lithium alloy V-1469 on the microstructure and microhardness has been studied. Hardening and one- and two-stage artificial aging with various holding times (from 1 to 12 hours) were carried out. Using optical and scanning electron microscopes, the microstructure was studied and a local chemical analysis of the phase components of the alloy was carried out. It is shown that with an increase in the time of one-stage artificial aging, the microhardness increases from 93 to 175 HV, and with an increase in the total exposure during two-stage aging, from 91 to 180 HV, as a result of structural-phase changes and an increase in the proportion of strengthening phases. Inclusions of a regular triangular shape, found after hardening, contain up to 17 % (by mass) of copper and have a size of 1.5-3.0 µm.