Yu Hong-Chen, Wang Hui-Yuan, Chen Lei, Zha Min, Wang Cheng, Li Chao, Jiang Qi-Chuan
Key Laboratory of Automobile Materials of Ministry of Education & School of Materials Science and Engineering, Nanling Campus, Jilin University, No. 5988 Renmin Street, Changchun 130025, China.
Materials (Basel). 2016 Mar 29;9(4):243. doi: 10.3390/ma9040243.
It is found that Li₂Sb compound can act as the nucleus of primary Mg₂Si during solidification, by which the particle size of primary Mg₂Si decreased from ~300 to ~15-25 μm. Owing to the synergistic effect of the Li₂Sb nucleus and adsorption-poisoning of Li atoms, the effect of complex modification of Li-Sb on primary Mg₂Si was better than that of single modification of Li or Sb. When Li-Sb content increased from 0 to 0.2 and further to 0.5 wt.%, coarse dendrite changed to defective truncated octahedron and finally to perfect truncated octahedral shape. With the addition of Li and Sb, ultimate compression strength (UCS) of Al-20Mg₂Si alloys increased from ~283 to ~341 MPa and the yield strength (YS) at 0.2% offset increased from ~112 to ~179 MPa while almost no change was seen in the uniform elongation. Our study offers a simple method to control the morphology and size of primary Mg₂Si, which will inspire developing new Al-Mg-Si alloys with improved mechanical properties.
研究发现，Li₂Sb化合物在凝固过程中可作为初生Mg₂Si的形核核心，借此初生Mg₂Si的颗粒尺寸从约300μm减小至约15 - 25μm。由于Li₂Sb形核核心与Li原子吸附中毒的协同作用，Li - Sb对初生Mg₂Si的复合变质效果优于Li或Sb的单一变质效果。当Li - Sb含量从0增加到0.2 wt.%，并进一步增加到0.5 wt.%时，粗大枝晶转变为有缺陷的截角八面体，最终转变为完美的截角八面体形状。随着Li和Sb的添加，Al - 20Mg₂Si合金的极限抗压强度（UCS）从约283 MPa增加到约341 MPa，0.2% 偏移屈服强度（YS）从约112 MPa增加到约179 MPa，而均匀伸长率几乎没有变化。我们的研究提供了一种控制初生Mg₂Si形态和尺寸的简单方法，这将激发开发具有改善力学性能的新型Al - Mg - Si合金。
