Synthesis of nanocrystalline AZ31 magnesium alloy with titanium addition by mechanical milling

Mechanical milling was used to prepare nanocrystalline AZ31 magnesium (Mg) alloy with titanium (Ti) addition. During milling, the crystallite size of the AZ31 Mg matrix decreased steadily with the increase of milling time. After milling for 110 h, the crystallite size of the Mg phase of the alloy with 18 wt.% and 27 wt.% Ti additions was refined to 86 nm and 66 nm respectively, leading to the formation of a nanocrystalline Mg matrix microstructure. Meanwhile, the size of Ti particles added in the alloy also decreased gradually with the increase of milling time, and the Ti dispersions presented a positive effect on the refinement of the Mg matrix grains. By milling for 110 h, the average size of Ti particles was refined to less than 1 pm in the AZ31 Mg alloy with 18 wt.% Ti addition. After mechanical milling, the as-milled powders were cold pressed into green compacts, and the mechanical properties were characterized by Vickers' hardness and uni-axial compressive tests. It was found that the micro-hardness of mechanically milled AZ31 Mg alloy with 27 wt.% Ti addition reached about 147 Hv, which was almost three times larger than that of the as-received AZ31 Mg alloy. Meanwhile, the yield strength of mechanically milled Ti-added AZ31 Mg alloy was seen to be as high as 293 MPa at room temperature and 60 MPa at 300 degrees C, respectively. (C) 2016 Elsevier Inc. All rights reserved.