Al-Cu- (Li) -Mg-Ag / TiB _{Composite Microstructure And Properties Of Its 2} Reaction

High-strength heat-resistant aluminum alloys were widely used in the aerospace industry. This subject fabricated2A42/TiB2composite by using in-situ synthesis TiB2particles in Al-Cu-Mg-Ag alloys, and prepared Al-Cu-Li-Mg-Ag alloys by cast-alloying. The microstructure evolution of hot deformation of TiB2reinforced aluminum matrix composite, as well as heat treatment process and microstructure properties of the Al-Cu-Li-Mg-Ag alloy were under discussion. Following conclusions can be drawn:(1) The constitutive equations of2A42/2%TiB2particles were established by true stress-strain curves. The hot deformation activation energy of alloy was313.87KJ/mol. Processing map at a strain of0.5indicated that optimum hot working regime for alloy is in the temperature range of430℃-460℃and strain rate of0.1s-1-1s-1.(2) PSN-DRX and CDRX occured before undergoing geometric DRX. DPN of Al2Cu(Ω and θ phases) and pre-existing of nano-size TiB2inhibit migration of SGBs and restrains geometric DRX, resulting in the increasing of activation energy of alloys.(3) The composite showed high ductility at room temperature. The mechanical properties of the composite decreased rapidly at the temperature above200℃.TiB2inhibit the precipitation of Ω nucleation, affecting the strength of the material at room temperature.(4) The homogenization process:450℃/16h+495℃/8h dual-stage homogenization; the heat treatment process:505℃/1h+100℃/24h. By this series of processing, the alloy showed both high strength and good ductility, with tensile strength of640MPa, yield strength of510MPa, elongation more than10%. Alloy exhibit excellent high temperature heat resistance, with tensile strength of297Mpa and10%elongation at300℃.(5) Pre-stretching process increased the tensile strength and yield strength of the alloy. After505℃/1h+pre-stretched3%+190℃/7h+100℃/24h heat treatment process, the tensile strength and yield strength were greatly improved, up to748.3Mpa and730.5Mpa.