晶粒细化能有效降低铸造缺陷，减小晶粒尺寸，是提高Al-Mg合金强度和塑性的有效途径。研究了Ti元素 对Al-5Mg 合金晶粒细化的影响规律和机理。 结果表明，Ti元素能够有效细化Al-5Mg合金晶粒尺寸， 与未添加Ti相 比，添加0.1%Ti(质量分数)的Al-5Mg合金的晶粒尺寸从143.4μm降至42.7μm。 其主要原因为Ti、Zr与Al原子结合 形成Al3 Ti、Al3 Zr、Al3 (Ti, Zr)颗粒能充当有效的异质形核核心，促进合金中细小、均匀等轴晶的形成。 当 Ti元素含量为 0.2%(质量分数)时，Al3 M 颗粒团聚粗化，形核位点数量减少，Ti元素细化效果降低，合金的晶粒尺寸增加到64.6μm。 当 合金中Al3 M相尺寸越小、数量越多，分布越弥散，其细化晶粒效果越好。

Grain refinement can enhance the strength and ductility of Al3 Mg alloys by reducing the number of casting defects and grain size. The effects of the addition of trace amounts of Ti on the microstructure and grain refinement mechanism of the Al-5Mg alloy were studied. The results show that the addition of the trace element Ti can refine the microstructure of the Al-5Mg alloy. Compared with that of the alloy without Ti, the grain size of the Al-5Mg alloy with 0.1 wt. % Ti decreases from 143.4 μm to 42.7 μm. The main reason for Ti refining grains is that Ti and Zr atoms combine with Al atoms to form Al3 (Ti, Zr), Al3 Ti, and Al3 Zr particles, which provide heterogeneous nucleation sites for Al atoms, promoting the formation of microstructures with uniform and fine equiaxed grains. When the Ti content is 0.2 wt. %, the grain size of the alloy increases to 64.6 μm, and the agglomeration and coarsening of the Al3 Ti, Al3 Zr, and Al3 (Ti, Zr) particles lead to a reduction in the number of heterogeneous nucleation sites and the effectiveness of the grain refinement of the Ti in the Al-5Mg alloy. The grain refinement effect improves as the size of the dispersed Al3 M phases in the alloy decreases and their quantity increases.