Study On Diffusion Behavior And Mechanical Properties Of Aluminium-Magnesium And Magnesium-Scandium

Aluminum alloys and Magnesium alloys have low density,strong hardness and wear resistance,corrosion resistance,oxidation resistance and are used in aerospace,ship traffic,daily life and other aspects.But because of the low melting point of Al-Mg which leads to the diffusion between the alloys more prone to occur.Because the mesophase generated by diffusion behavior is a more brittle intermetallic compound,this leads to the failure of the whole part.In order to avoid the diffusion behavior effectively between alloys,it is urgent to study the diffusion behavior between metals.In this paper,the binary diffusion behaviors of Al-Mg and Mg-SC are studied as follows.In the Al-Mg system:??The diffusion activation energies of ?-phase(Al3Mg2)and?-phase(A112Mg17)were calculated according to the diffusion behavior of pure Al-Mg diffusion couples.And the mechanical properties including nano-indentation hardness and elastic modulus of different phases were measured.??A molybdenum wire was added to the diffusion couple interface to determine the original interface movement after diffusion,and to confirm the reason for the formation of impurity layers at the same time.??In order to further confirm the change mode of the region phase between ? phase and y phase and the temperature of reaction or decomposition,the modified high vacuum argon arc melting method was used to prepare the alloy samples with accurate composition,and the composition of the phase was analyzed after aging at different temperatures.Combined with DSC analysis of heat absorption and exothermic during phase transition,the modified phase diagram was proposed.At the same time,the density of the alloys at different temperatures were measured,which provided a reliable reference for its future application in industry.In the Mg-Sc system:??The pure element diffusion couple of Mg-Sc was prepared.According to the growth rule of the generated phase,the type of the formation phase was judged,the diffusion activation energy of ?-Sc solid solution phase was calculated under the same diffusion type,and the approximate formation temperature of y-phase(MgSc)was indirectly determined.In the same way,the mechanical properties of the regions with different scandium compositions were measured and the nano-hardness and creep curves corresponding to the composition were obtained.??Because the Mg-rich side of Mg-Sc alloy exhibits excellent elastic recovery behavior at room temperature,the relationship between creep behavior and Sc concentration in.Mg-Sc alloy was deeply studied,and the recovery rate under optimum composition was calculated by experimental data.