Research On Ultra-fine Grains And Mechanical Property Of Al-Mn Alloy

Al-Mn alloy is significantly characterized by excellent corrosion resistance, good welding and workability performance, but also has high plasticity, good thermal and conductive properties. Therefore, Al-Mn alloy has been widely used as general purpose alloys with good corrosion resistance of moderate intensity alloy for moderate-strength applications requiring good workability.The accumulative roll bonding process has been applied to Al-Mn and Al-Mn-0.1Sc-0.1Zr alloy. X-Ray diffraction(XRD), optical microscope(OM) and transmission electron microscopy(TEM) were applied to observe the interface morphology and microstructure evolution of ARBed sheets. The tensile strength, yield strength, hardness and other mechanical properties of the sheets were studied. And then further discussed the relationship between mechanical properties and microstructural evolution of the ARBed sheets.The research results show that the Al-Mn and Al-Mn-0.1Sc-0.1Zr alloy were processed by ARB at 400℃ successfully, and thickness of the alloy sheets is 1 mm. After four cycles of ARB, most regions of the Al-Mn and Al-Mn-0.1Sc-0.1Zr alloy consisted of equiaxed ultra-fine grains with high angle boundaries. Equiaxed ultra-fine grains of 0.4μm and 0.38μm were obtained in the alloy after 8 cycle ARB. The grain size was refined significantly. The residual strain in the ARBed alloy was increased, as the increase in dislocation density and lattice parameter of matrix. The XRD results show that the peak for(111/222) and(200/400) of the ARBed alloy increased significantly, and shifted to smaller diffraction angles of peak center position with ARB cycles increased.After severe plastic deformation, the mechanical properties Al-Mn and Al-Mn-0.1Sc-0.1Zr alloy sheets were improved, the yield strength and tensile strength increased with the increase of ARB cycle significantly. The elongation to failure of ARB samples decreased greatly after 1 cycle and then increased little until to 8 cycles. Al-Mn-0.1Sc-0.1Zr alloy strength of different ARB cycle were significantly higher than that of Al-Mn alloy, and after the fifth cycle, tensile strength difference reached at 48 Mpa. Compared with Al-Mn alloy not adding alloying elements Sc and Zr, dislocation and the grain density of Al-Mn-0.1Sc-0.1Zr alloy is higher in the microstructure of different ARB cycles.