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In Situ Particle Reinforced Magnesium Matrix Composites and deformation behavior

Author: WuZuoZuo
Tutor: ZhangXingGuo；FangCanFeng
School: Dalian University of Technology
Course: Materials Physics and Chemistry
Keywords: Magnesium Matrix Composites Mg-RE alloys TiB2 particles Al2 Y, Gd particles Hot extrusion
CLC: TB331
Type: Master's thesis
Year: 2011
Downloads: 111
Quote: 1
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Abstract


In the automotive and aerospace industries, as the structure of the material needs to have a lighter quality and high strength, it can be used as a structural element of magnesium alloys are high hopes. However, the relative intensity of the magnesium alloy is still low, limiting its range of applications. High rare earth content of the magnesium alloys exhibit very excellent mechanical properties, but the high RE means a high manufacturing cost, is not conducive to universal application. Therefore, reducing the rare earth content while maintaining a certain performance become Mg-RE alloy key development directions. In addition, the material has not been carried out by workers in Mg-RE alloy matrix composites. Accordingly, the paper will high-toughness magnesium alloy and composite materials technology, select Mg-Gd-Y-Zn alloy and Mg-Gd-Y-Zn-Zr alloy matrix reinforced particles in situ study and performance of their organizations effects and examine hot extrusion and T5 aging treatment on the composite effect; also studied TiB2/AZ31 composite microstructure and properties after hot extrusion, and one of particle reinforced and deformation mechanism is discussed. Through the above study reached the following conclusions: 1. Use SHS - mechanical mixing technology, Mg-Gd-Y-Zn alloys and Mg-Gd-Y-Zn-Zr alloy by adding Al-Ti-B precast block after was prepared by a variety of in-situ particle reinforced Mg-RE based composites. Situ TiB2 particles and Al2 (Y, Gd) introduce significant refinement of the as-cast Mg-Gd-Y-Zn alloy microstructure, a-Mg grain morphology of dendrites from the coarse to fine equiaxed crystal. Mechanical properties has also been improved to some extent. But in Mg-Gd-Y-Zn-Zr alloys, due to the consumption of Zr refiner, microstructure and properties were reduced; 2 in situ particle reinforced Mg-Gd-Y-Zn-based composite materials for hot extrusion after extrusion situ particle arranged parallel to the extrusion direction, enhanced dynamic recrystallization occurs around the particles. Hot extrusion makes the mechanical properties of composite materials have a more substantial upgrade. Which, 2wt.% Al-Ti-B/Mg-Gd-Y-Zn matrix composite tensile strength after extrusion 330 MPa, elongation of 13.3%, compared with the matrix alloy extruded increased by 16.6% and 38.5%, respectively, than the cast composites increased 67.5% and 52.4%; 3. Mg-Gd-Y-Zn matrix composite hot extrusion after 200 ℃ / 50h artificial aging treatment. This aging system for extruded composite microstructure less impact strength of the material slightly improved. Wherein, 2wt.% Al-Ti-B/Mg-Gd-Y-Zn matrix composite tensile strength after aging 342 MPa; addition, significantly improved aging 6wt.% Al-Ti-B/Mg-Gd-Y -Zn matrix composites elongation (up 15.2%), compared with extruded and cast were increased by 56.7% and 360.6%; 4 hot extrusion can be significantly refined TiB2/AZ31 magnesium matrix composite microstructure, TiB2 particles to improve the distribution uniformity of the macro. TiB2/AZ31 magnesium matrix composite extrusion deformation slip and twinning are the main deformation mechanism of deformation of the material depends not only on the respective slip and twinning alone, there are between slip and twinning together.

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