Investigation Of Anisotropy Of Microstructures And Mechanical Properties Of The Rolled Ti/Al/Mg/Al/Ti Composite Plate

Mg alloys have become a very important new green lightweight structural material,as the demand for lightweight materials in the fields of transportation and aerospace continues to increase.However,the disadvantages of Mg alloys in terms of corrosion resistance,strength,stiffness and surface modification greatly limit its wide application.Ti alloys can be used to improve the defects of Mg alloys because it is to be complementary to Mg alloys in these respects.But it is difficult to directly combine the two materials as the low solid solubility and they cannot react to form compounds.In order to improve the bonding strength of interface,Al or Al alloys can play an intermediate junction role to prepare Ti/Mg composite plates.Here,the Mg/Al/Ti composite plate was prepared by hot rolling.The microstructures and mechanical properties of the Mg/Al/Ti composite plate and the AZ31 component sheet?the reduction was same to the actual reduction of the Mg layer in the composite plate?in different directions were carried out and the anisotropic behavior of rolled plates was discussed.The microstructures and mechanical properties of annealed Mg/Al/Ti composite plate and AZ31 sheet in different directions were studied and the effect of annealing on sheet anisotropy was explored.When the rolling temperature was 450?,the reduction was 50%and the rolling rate was 4.08 m?min^-1,the Ti/Al/Mg/Al/Ti composite plate was successfully produced.In the rolled composite plate,the interface bonding was good and there was no compound of interlayer at the interface.Due to the difference in mechanical properties of the different metals,the Al/Ti interface and the Mg/Al interface displayed the linear and the wavy morphology,respectively.After annealing at 200? for 1 hour,no interlayer compound was formed at the interface.The analysis of microstructure and mechanical properties of the composite plate shows that:the microstructure of the Ti layer exhibited equiaxed grains in different directions.The microstructure of Mg layer is different in different directions:near the interface,in the RD direction,the degree of dynamic recrystallization was the largest,the microstructure was dominated by small crystal grains,and the texture intensity was the smallest.The microstructures of TD direction and the 45°direction possessed a few deformation grains,which was characterized by strong basal texture.In the central region,the microstructure was dominated by large grains and some small grains were still present.The?0002?pole figure exhibited the basal texture.Regardless of the interface or the central region,the content of the low angle grain boundary,the volume fraction of tensile twin and the texture intensity were different in different directions.In different directions,the fracture of composite plate can be segmented into five stages.Mechanical properties had obvious anisotropy:the highest strength was in RD direction,the best elongation was in 45°direction.The indexs of plane anisotropy?IPA?of tensile strength,yield strength and elongation were 11.3%,18%and12.56%,respectively.The analysis of microstructure and mechanical properties of AZ31 sheet shows that the microstructure in different directions showed the bimodal grain structure composed of large grains and small grains and the?0002?pole figure exhibited the basal texture in all directions,but the degree of dynamic recrystallization,the content of the low angle grain boundary,the volume fraction of twin and the texture intensity were different in different directions.The mechanical properties of the rolled AZ31 owned obvious anisotropy,its degree of anisotropy was more serious than that of composite plate.The IPA of tensile strength,yield strength and elongation were 14.19%,11.4%and 34.28%,respectively.After annealing at 200? for 1 hour,in the Mg layer of the composite plate and the AZ31 sheet,the deformed grains shrank or even disappeared.A large number of small equiaxed grains appeared and the microstructure tended to be uniform.The strength of the plate decreased and the elongation increased.Recovery and static recrystallization occurred during the annealing process.The difference of microstructure,texture and mechanical properties of the composite plate and AZ31 plate was weakened.