Microstructure and Mechanical Properties of Selective Laser Melted Al-2.51Mn-2.71Mg-0.55Sc-0.29Cu-0.31Zn Alloy Designed by Supersaturated Solid Solution

Selective laser melting (SLM) of aluminium alloys for lightweight application is arousing widespread interest, but the available alloy compositions are limited due to unsatisfactory mechanical performances. The rapid solidification of SLM provides a pathway to design a novel alloy composition with extended solubility. This strategy is demonstrated by an additively manufactured novel Al-2.51Mn-2.71Mg-0.55Sc-0.29Cu-0.31Zn alloy with the supersaturated solid solution in the present study. The microstructure of as-build sample is characterized with multi-modal grains with the fine equiaxed grain (FEG, ~ 800 nm) at molten pool boundaries, coarse equiaxed grain (CEG, ~ 2 μm) and columnar dendrites (CD, ~ 4 μm) inside the molten pool, which relates to the precipitations type and distribution. It is observable that Al₃(Sc, Zr) precipitation particles with the size of ~ 50 nm are dispersed in the FEG zone, while the interior of CEG shows no Al₃(Sc, Zr) particle which only exists at the CEG boundaries. Regardless of FEG, CEG or CD, the slender Al₆Mn precipitation with the length of ~ 500 nm is distributed along the grain boundaries. Meanwhile, a lot of vacancies and thickness fringes are detected in the FEG zone, which confirms the supersaturated solid solution in laser rapid solidification. The ultimate tensile strength and yield strength of the as-printed sample are ~ 380 MPa and ~ 330 MPa, respectively, with elongation ~ 14%, which increase to ~ 440 MPa and ~ 410 MPa with a reduction of elongation to ~ 9% after heat treatment.     

PEMFC可视化技术的研究现状与展望

可视化技术是研究质子交换膜燃料电池(PEMFC)内部水管理的重要技术之一.从PEMFC可视化技术的研究意义出发,对PEMFC可视化技术的研究现状进行归纳,介绍了现有PEMFC可视化方法的优势以及存在的问题,对试验过程中PEMFC可视化方法遇到的问题进行了总结并提出解决方法,对提高燃料电池可视化技术具有指导意义.     

Diffusivity of Ti-Ni Diffusion Couple Enhanced by Pulse Current During Spark Plasma Sintering

Metallurgical and Materials Transactions B - The effect of pulse current (PC) on the interdiffusion of Ti-Ni system was investigated under spark plasma sintering. The growth rate of Ni-Ti...