Papers by Author: Yan Ping Zhu

Abstract: This paper investigates the microstructure, mechanical properties and creep behavior of Mg–Al–Ca alloys with different Ca content. SEM and EDAX analyses show that the dominant second phase in the as-cast Mg–Al–Ca alloys is Al2Ca, which distributes at the grain boundaries and disperses in the grain interior as well. Both the elevated tensile strength and the creep resistance of Mg–Al–Ca alloys obviously increased with increasing Ca at high temperature. TEM analyses reveal that finer Al2Ca particles with an average size of 0.02 µm precipitated dynamically during the creep process. Selected area electron diffraction (SAD) patterns show that the dynamic Al2Ca precipitates have a coherent interface with matrix as (0110) Mg // (220) Al2Ca, [2110] Mg // [112] Al2Ca. The strengthening mechanism of Mg–Al–Ca alloys at elevated temperature was discussed.

Abstract: Formation behavior and performances of anodic film grown on AZ31B alloys were systematically studied in Na2SiO3 system electrolyte with varying triethanolamine (TEA) content. The growth behavior and appearance of anodic film were significantly affected by the TEA content. The film growth speed increased because of the addition of TEA. Whitish gray lubricous barrier-type film were obtained in the electrolyte with TEA. The film density was obviously increased by the addition of TEA. Moreover, the film produced in electrolyte with TEA possessed a high degree of corrosion resistance and obviously better than that formed in electrolyte without TEA. EDX analysis indicates that, as the concentration of TEA increased, the contribution of the elements from the base alloy increased.

Abstract: Effects of variable La/Ce ratio on microstructure and mechanical properties of Mg-5Al-0.3Mn-1RE alloys were investigated. The results indicated that pure La or pure Ce can improve ultimate strength and yield strength of AM50 effectively without obvious decrease of elongation, and the effect of La is better than that of Ce. However, addition of La and Ce together deteriorates the mechanical properties of AM50, and the valley of mechanical properties mostly appears on La:Ce= 1:1. The existence of coarse skeleton-like phase and less amount of Mg17Al12 phase is responsible for this.

Abstract: Mg92Zn6Y1.5Zr0.5 alloy was extruded at 300, 350, 400 ı. Then, the alloy was aged at 180 ı. The microstructure and mechanical properties of the extruded alloy and aged alloy were investigated. The precipitation behavior of aging process was investigated. The increase of yield strength at room temperature and ultimate strength at elevated temperature after the aging process has been ascribed to the strengthening effect of these precipitates.

Abstract: Purification fluxes JDMR-1 containing B2O3 and JDMR-2 containing Na2B4O7 were developed for magnesium alloy. Density, viscosity and melting points of the two fluxes were measured. In the magnesium alloy iron concentration decreased from 0.024% to 0.004% and 0.001%, and average volume fraction of nonmetallic inclusions from 2.06% to 0.86% and 0.23% after JDMR-1 and JDMR-2 processing, respectively. Corrosion resistance and tensile properties of the magnesium alloy were greatly improved. Iron reduction mechanism was studied thermodynamically.