The Preparation And Characterization Of Al-13Mg-xMn-yRE Alloys

Al-Mg alloys are widely used in industry because of their favorable properties such as low density, high corrosion resistance and excellent mechanical properties. On the base ofЛ-27 alloy, the transition elements and alloying elements were adjusted, and the RE elements were added to improve the microstructure and mechanical properties as well as dumping capacities. A new type of alloy was developed with high performance price ratio, medium strength and corrosion resistance.The microstructure of the Al-13Mg-0.8Mn-RE(La,Ce,Y,Dy,Lamm and Ymm)alloys have been investigated by optical microscope, X-ray diffraction instrument, scanning electrical Microscope, transmission electron microscope. The mechanical properties of the alloys have been tested by the universal mechanical determination. It shows that the phase composition in the as- cast alloys are mainly consisted ofα-Al,β(Al3Mg2),Al6Mn and Al-RE phases. Theβ(Al3Mg2)phases segregate around the boundary as discontinuous net eutectic structure. The size of phase is coarse. A part of Mn and RE elements solute in the matrix, Others are generated the massive Al6Mn and spotted Al-RE particles which are sporadic distributed in the boundary and inside of the grain.The properties of the alloys are different with the adding of the various of RE elements. The results show that the Al-13Mg-0.8Mn-0.8Y alloy shown highest hardness, ultimate compressive strength and compressibility, and the values are 138 HB, 533 MPa and 22.2% respectively. Because of the presence of solute elements of Y which enhance the degree of super cooling in the diffusion layer ahead of the advancing solid/liquid interface, the microstructure of dendrite was refinement.It is believe it is mainly due to the addition of the Y greatly refine the dendrite, which increases the obstacle to the dislocation sliding. Moreover, the high hardness of Al2Y phase distributed in the alloys can act as a dispersion strengthening phase in the matrix. The compressive fracture surface indicted that some cleavage planes and shrinkage cavities were observed. It was confirmed that the investigated alloys belong to typical brittle cracking mode.