AX series magnesium alloy and heat-resistant

Title: AX series magnesium alloy and heat-resistant properties of
　　Author: Liu Yang
　　Degree-granting units: Jiangxi University of Science
　　Keywords: AX series heat-resistant magnesium alloy;; mixed rare earth metals;; heat treatment;; microstructure;; mechanical properties
　　Summary:
　　In this paper, AX-series heat-resistant Magnetic lifter magnesium alloy AX51 (Mg-4.6Al_-0.8Ca-0.24Mn), AX52 (Mg-5.0Al_-2.0Ca) two grades as a research base, using the La-rich Ce-rich mixed rare earth metals (MM) as an additive, respectively, by adding 1.0% MM, 1.5% MM, 2.0% MM to analyze the organization and its mechanical properties.
　　X-ray fluorescence analysis using the proceeds to test the melting of the alloy composition and expected are the same, through the optical microscope to observe the microstructure and refinement, using X-ray diffraction (XRD) phase analysis of alloy composition and the use of scanning electron microscopy (SEM), test spectrum (EDS) and other analytical techniques to study the corresponding fracture mechanism of heat-resistant magnesium alloy and heat-resistant mechanism. Comparative analysis of the state-cast and heat-treated alloy of these two tests and performance impact.
　　Experiments show that the addition of mixed rare earth MM and properties of two alloys are significantly improved. MM were added after a certain amount of alloy microstructure grain structure size are to be significantly refined, and the emergence of Al_4Ce and Al_4La heat phase. In addition, the AX51 and AX52 alloy alloys, phase composition is not exactly the same. AX51 magnesium alloy in the heat, the heat does not appear Al_2Ca phase, but there Al_2Ca in AX52 alloy phase appears. This is mainly related to the ratio of the Ca and Al_. When the Ca / Al_ <0.2, when, Ca can refine Mg-Al_ matrix, can improve the β-Mg_ (17) Al_ (12) relative to the melting point and thermal stability, but does not, and Mg, Al_ form any compound, and major soluble α-Mg or β-Mg17Al_12 in; when 0.2
　　This article also test alloys were investigated at room temperature mechanical properties and high temperature mechanical properties. Of MM in different content to add, the same alloy in 1.5% of MM added at room temperature and high temperature mechanical properties of the optimal; Add MM in the same content under, AX52 AX51 alloy than the room temperature mechanical properties of the alloy is worse, high-temperature mechanical properties better, which is the main phase with Al_2Ca heat generation. In addition, AX51 alloy before and after adding MM were subject to high temperature tensile fracture mode of cleavage fracture and ductile fracture, AX52 alloy fracture before and after adding MM methods were brittle and ductile fracture. Changes mainly due to the addition and the amount of the Ca, Ca by adding excess thermal cracking of the alloy will increase.
　　Compared to the as-cast alloys and mechanical properties, heat treatment of the two alloys and mechanical properties are improved significantly. Found through the solution process, alloy with time and slowly dissolved in 420 ℃ × 48h when the http://www.999magnet.com/products/131-magnetic-lifter organization dissolved more completely, especially the β-Mg_ (17) Al_ (12) phase, is almost completely dissolved in α-Mg matrix, only a small amount of rare-earth heat phase Al_4Ce and Al_4La not completely dissolved; through the aging process found that the alloy has also changed over time to increase significantly, when the time is greater than 8h, the organization began to precipitate β-Mg_ (17) Al_ ( 12) phase, especially in the 180 ℃ × 24h, there are still rare-earth phase Al_4Ce and Al_4La heat precipitation.
　　Heat treatment on the mechanical properties of alloys have a greater impact. Compared to the cast, after the solid solution at room temperature or high temperature conditions, regardless of the alloy σb, σ0.2 and δ were up, mainly with the β-Mg_ (17) Al_ (12) phase and rare-earth phase Al_4Ce and Al_4La of heat dissolve the. Conditions in the aging process, σb and σ0.2 rise, and δ decreased significantly, but better than the solution process to improve the alloy σb and σ0.2. The reason is that the precipitation of fine β-Mg_ (17) Al_ (12) phase, Al_2Ca a large number of rare-earth phase and heat-resistant phase Al_4Ce and Al_4La pinning effect on the organization to prevent the grain boundary slip and climb, thus affecting the alloy mechanical properties.
　　Degree Year: 2010