Y element of ZK20 magnesium alloy and the properties

Title: Y element of ZK20 magnesium alloy and the properties
　　Author: Lu Riverside
　　Degree-granting units: Chongqing University
　　Keywords: Mg-Zn system magnesium alloy;; rare earth Y;; organization;; performance;; extrusion temperature
　　Summary:
　　As a lightweight magnesium alloy material has broad application prospects. However, because of an hexagonal close-packed lattice structure and plastic deformation capacity of less than aluminum and steel, plastic processing of magnesium alloy increases the difficulty of preparation and production costs, this new type of magnesium alloys in recent years, research Magnetic lifter and development, has begun to pay attention through the wrought magnesium alloy in alloy design and introduction of new deformation technology, etc., in ensuring the strength of magnesium alloy to improve the processing of plastic deformation. Magnesium alloy Mg-Zn system because of its high strength, good plasticity become a research hotspot. But the wider application of Mg-Zn alloys with higher zinc content of high-strength magnesium alloy, plastic deformation is poor.
　　For the development of high plastic deformation of magnesium alloy, this low zinc content in Mg-Zn-Zr alloy after adding Y to start a number of features and advantages of the study. By adding MgY alloy ZK20 alloy, obtained with different mass percentage Y of semi-continuous slab, research on low-Zn-Mg Y Zn Zr alloys as-cast structure and mechanical properties and mechanism of the law, access to low-Zn conditions under the Mg-Zn alloy containing zirconium type Y with the Y content relative to the variation of overall performance has been optimized alloy composition; optimized squeeze even before the annealing process, and after homogenization annealing with different mass percentage of Y alloy extrusion billet to study the different mass percentage of Y and mechanical properties of extruded products, the impact of laws and mechanisms, combined with the mechanical properties and the cost of adding alloying elements, select the best alloy composition. Use ZK20 +0.9% Y alloy extrusion process optimization test.
　　The results show that: when the yttrium content changes from 0.9% -1.9%, the alloy was cast structure refinement, continuous intergranular compounds was fine mesh; when the yttrium content of 3.7%, the crystalline intermetallic compounds are not contiguous, the coarse mesh like. When the Y from 1.9% to 5.8%, the cast alloy strength gradually increased. Y content of 0.9%, Y-refining effect on the organization and the appropriate W-phase content of the plastic favorable elongation reached the maximum 24.8%; Y content of 3.7% when, W-phase due to the number of X-phase the emergence of reduced intergranular compounds into the distribution network is not http://www.999magnet.com/products/131-magnetic-lifter continuous, beneficial for plasticity, the best alloy mechanical properties, tensile strength of 232MPa, yield strength of 124 MPa, elongation of 23.5%. Add Y element will increase the flow stress of the alloy, when the Y content of 3.7%, the flow stress reaches its maximum 85.7MPa. After 420 ℃ × 12h homogenization, ZK20 +3.7% Y alloy W-phase can be overcome. After a 480 ℃ hot extrusion, add Y alloy elements significantly higher than ZK20 alloy grain refinement, because homogenization to eliminate some of the organization and composition segregation segregation, coupled with hot extrusion deformation recrystallization refinement results, the deformation alloy strength than the cast alloy are greatly improved. As the Y content increases, the deformation of alloy strength and ductility are gradually improving, Y content of 5.8%, the maximum tensile strength of 279MPa, when the Y content of 5.8%, the extension rate of 28.1%. Study, X-phase alloys the presence of beneficial plasticity, when the Y content exceeds 3.7%, the alloy with X-elongation phase content increases. Optimization of the ZK20 +0.9% Y alloy after hot extrusion 330 ℃, the alloy strength of 322MPa, elongation 21.9%.
　　Degree Year: 2010