The Experimental Investigation Of Liquidus Projection And Isothermal Section At 400? Of The Al-Cu-Mn-Mg Quaternary System

The phase diagram of the Al-Cu-Mn-Mg system is very important for 2XX.0 and 2XXX commercial aluminum alloys,but so little literatures aiming at this system.Thus we have investigated the liquidus projection and the isothermal section at 85 at.%A1 and 400? of the Al-Cu-Mn-Mg quaternary system so as to provide the relative phase diagram and thermodynamic parameters for the improvement and development of the alumina database.On the basis of the calculated phase diagram,the key component points are selected for the experiment.The alloys of the Al-Cu-M n were prepared with Electric Arc Furnace.After that,the ternary alloy were puted into sealed Ta tube in muffle furnace with Mg and we can successfully make the quaternary alloy.Then using the SEM and XRD analyze the morphology and detect the phase of equilibrium alloys.And the invariant reaction temperature of the as-cast alloy were measured with the differential scanning calorimeter(DSC).The isothermal section,solidification sequence and other related information of Al-Cu-Mn-Mg quaternary were deduced according to all the experimental data and literature information.The experimental results show that the isothermal section of the Al-Cu-Mn-Mg quaternary system contains three binary compounds and four ternary compounds,like Al2Cu,Al4Mn,Al6Mn,?i-Al28Cu4Mn7,?2-(AlxCu1-x)49Mg32,?3-Ali8Mg3Mn2 and S-Al2CuMg.It has three three-phase region and five four-phase region.No quaternary compounds were found in this system.The experimental phase diagram and the calculation of the phase diagram are roughly consistent.And there are some differences in phase composition.In addition,the Al-Cu-Mn-Mg quaternary system has five eutectic reactions and a quasi-peritectic reaction in the solidification process.The six reactions are as follows:L?(Al)+ A12Cu + ?i(541 ?),L?(Al)+ S(507?),L ?(Al)+ Al2Cu +S(500?),L?(Al)+ S + ?1(498.7?),L ?(Al)+ Al3Mg2 + ?2(442?),L + S?(Al)+ i2(464?).Of course,the above reactions are not necessarily the invariant reactions of this system,but only when the phase change occurs during solidification.