rare earth element Er on the Mg-4Y-3Nd-0.5Zr alloy and properties

Title: rare earth element Er on the Mg-4Y-3Nd-0.5Zr alloy and properties
　　Author: Xiao-Fang Wu
　　Degree-granting unit: Taiyuan University of Technology
　　Key words: magnesium alloy;; microstructure;; fracture mode;; time;; mechanical properties
　　Summary:
　　In cast magnesium alloys containing heavy rare earth Mg-RE alloys the most outstanding overall performance. One, Mg-Y-Nd system with excellent performance magnesium alloys. Er rare earth elements with hcp structure, the maximum solid solubility of Mg is 32.7 mass%, more than the Y and Nd elements in solid solution in magnesium easy, it is Magnetic lifter considered as the fourth-element Er added to the Mg-Y-Nd alloys in the study by adding Er element of the matrix organization and performance.
　　In this study, Mg-4Y-3Nd-0.5Zr as matrix, in which adding different content of Er, the use of SF6 + Ar mixed gas melting, prepared by gravity casting new type of Mg-4Y-3Nd-xEr-0.5Zr ( x = 0,1,2,4) alloys, integrated application metallographic analysis, spectrum analysis, mechanical analysis and fracture surface analysis used to study the state-cast and heat-treated alloy microstructure and mechanical properties.
　　The results show that Mg-4Y-3Nd-xEr-0.5Zr (x = 0,1,2,4) alloys in a non-equilibrium solidification process, the alloy-cast equiaxed dendrite is mainly α-Mg phase, and a granular Mg24Y5 and mesh Mg41Nd5 second phase intermetallic compounds produced. Er element decreases the Y, Nd solubility of elements, and with the added amount of the increase in Er, second-phase intermetallic compounds and Mg41Nd5 Mg24Y5 increasing.
　　Mg-4Y-3Nd-xEr-0.5Zr alloy cast by 525 ℃ 12h solution treatment completely eliminated after dendritic organization, the grain boundary is evident, but the precipitate particles remain. With the increase of Er content alloy grain size changed little, while the second phase of undissolved particles are gradually increased. Alloy isothermal aging at 250 ℃ soon reach the peak time, peak aging state of Mg-4Y-3Nd-xEr-0.5Zr (x = 0,2) alloy thin sheet of a small amount of elongated precipitates, such precipitates as Mg24Y5 intermetallic compounds is a major factor in age-hardening alloys. Peak aging state Mg-4Y-3Nd-xEr-0.5Zr alloy containing Er compounds not found, discovered and Mg41Nd5 granular compound Mg24Y5 intermetallic compounds. Therefore, the main effect Er solid solution strengthening effect, Y mainly from the precipitation strengthening effect.
　　Tensile test shows that: Er http://www.999magnet.com/products/131-magnetic-lifter content increases strength of the cast alloy increase after the first lower tensile strength alloy after aging treatment no regular trend. When the Er concentration to 2 mass%, the peak-cast state and time have reached the maximum tensile strength were 151MPa and 247MPa.
　　Fracture analysis showed that:-cast Mg-4Y-3Nd-xEr-0.5Zr (x = 0,1,2,4) alloys subject to dissociation of the fracture mode fracture, the peak aging state of the alloy fracture intergranular fracture along the way, the solution cleavage fracture, cleavage + intergranular fracture and quasi-cleavage fracture.
　　Degree Year: 2010