Effect of La/Nd ratio on microstructure and tensile properties of AZ91-RE alloys
(1. School of Materials Science and Chemical Engineering, Harbin University of Science and Technology, Harbin 150080, China;
2. Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, China;
3. School of Intelligent Manufacturing, Huzhou College, Huzhou 313000, China)
2. Key Laboratory of Advanced Manufacturing and Intelligent Technology, Ministry of Education, Harbin University of Science and Technology, Harbin 150080, China;
3. School of Intelligent Manufacturing, Huzhou College, Huzhou 313000, China)
Abstract: The effect of La/Nd ratio on the microstructure and tensile properties of AZ91-RE alloys was studied. Typical characterization was performed to analyze the volume fraction, mean nearest neighbor distance (NND), and number density of the secondary phases. First-principles calculations were employed to determine the formation enthalpy, mechanical and thermodynamics properties of the secondary phases. The results demonstrate that the alloy with a mass fraction ratio of La to Nd (wLa/wNd) of 3？2 exhibits the finest average grain size, the smallest mean NND, and the highest total number density of secondary phases. The calculations indicate that the formation of Al11La3 and Al2Nd is energetically favorable. Furthermore, Al11La3 and Al2La display significantly superior deformation resistance, shear deformation resistance, solid stiffness and thermal stability compared to other secondary phases. Therefore, increasing the content of Al11La3 and Al2La phases contributes to improving the mechanical properties of AZ91-RE alloy.
Key words: AZ91 alloy; microstructure; tensile properties; first-principles calculation; electronic structure; thermodynamic properties