Contain Trace Amounts Of Scandium, Zirconium, Al-cu-mg Alloys And Performance

This article studied the microstructure and properties of two kinds of Al-Cu-Mg-Zr and Al-Cu-Mg-Sc-Zr alloy at different treatments by conductivity measurement,testing mechanical properties,optical microscope(OM),X-ray diffraction(XRD) and transmission electron microscope(TEM).The heat-treatment regimes were optimized,the influence of element Sc and Zr on fracture mechism and strengthing mechanisma of Al-Cu-Mg aluminum alloys containing element Sc and Zr was discussed.The result shows that:(1) The suitable homogenization temperature and time of the Al-Cu-Mg-Sc-Zr alloy are 320-360℃and 8 hours;the suitable homogenization temperature and time of the Al-Cu-Mg-Zr alloy are 360-400℃and 8 hours.(2) At the condition of T3,tensile strength,yield strength and elongation of the Al-Cu-Mg-Sc-Zr alloy is 472MPa,383MPa,18.1% respectively,tensile strength,yield strength and elongation of the Al-Cu-Mg-Zr alloy is 467MPa,372MPa,17.2%respectively;At the condition of T4,ensile strength,yield strength and elongation of the Al-Cu-Mg-Sc-Zr alloy is 448MPa,292MPa,22.4%respectively,tensile strength,yield strength and elongation of the Al-Cu-Mg-Zr alloy is 455MPa,300MPa,23.8%respectively.(3) There are strong ageing strengthening characteristic in Al-Cu-Mg-Sc-Zr alloy and Al-Cu-Mg-Zr alloy,when aging at the temperature of 180℃,190℃and 200℃.The main phase of precipitation strength of the alloy is S'phase.The suitable ageing treatment of the alloy is ageing at 190℃for 4h.At this condition,tensile strength,yield strength and elongation the Al-Cu-Mg-Sc-Zr alloy is 421MPa,344MPa, 8.9%respectively,tensile strength,yield strength and elongation the Al-Cu-Mg-Zr alloy is 441MPa,355MPa,9.6%respectively.(4) The minor Sc,Zr exist in the Al-Cu-Mg alloy in the form of secondary Al₃(Sc_xZr_1-x) particle,this particle is coherence with matrix,it can strongly pin up the dislocation and sub-boundaries in hot procedure, restrain the migration of boundaries and the growth of subgrain,and partly inhibit the recrystallization of the alloy during high-temperature solution.(5) The strength of the alloys mainly come from solution strengthening of Cu and Mg,precipitation strengthening of Al₃(Sc_xZr_1-x) and substructure strengthening in hot procedure.