Effects Of Re,Sb On The Microstructure And Properties Of AZ31 Magnesium Alloy

Magnesium alloys possess many advantages, such as low density, excellent damping capacity, good electromagnetic shielding and high specific strength. Being regarded as the most promising green material of the 21st century, it has bright promise for magnesium alloys to be widely used in aviation, spaceflight, vehicle and electrommunication. But because of its poor plastic deformation ability and corrosion resistance, low yield stress and fracture toughness, the use of magnesium alloys is limited for a long time. AZ31 alloy is one of the most useful deformation magnesium alloy, In order to solve the problem in application and in processing, we use rare earth alloying and spheroidize rare earth rich phase, to improve mechanical property of AZ31 alloy in this dissertation.In this dissertation, the influences of the mixed addition of RE and Sb on the microstructure, mechanical property, corrosion resistance, the calibration acicular-shape rare earth rich phase and spheroidizing rare earth rich phase of AZ31 magnesium alloy are systematically studied by measurements of optical microstructure, X-ray diffraction, scan electric microscopy, microstructure at elevated temperature, microhardness, tensile test, impact toughness, corrosion potential, polarization curves and salt-spray corrosion rate.The small addition of RE can decrease the crystal grain size of the alloy remarkably, the more RE, the less crystal grain size. The average grain size is 35μm and the network like β phases are collapsed, dispersed with the l%RE.But excessive RE, the average grain size is not low, acicular-shape rare earth rich phase dispersed in grain boundary and rend basal body of the alloy, occur stress concentration.The mixed addition of RE and Sb can get a better effect on decreasing the crystal grain size and the everage size is only 30μ m. We fond the rare earth rich phase promoted heterogeneous nuclei that mainly caused the refinement. It can remove negative effect on plastic property and stress.The small addition of RE can increase the mechanical properties. When add 1.0%...