Grain refinement of Mg−Al binary alloys inoculated by in-situ oxidation

Mg−Al二元合金原位氧化孕育细化

Utilizing oxide inclusion to induce heterogeneous nucleation event is an available method to achieve grain refinement.In this study,Mg−Al binary alloys were refined by inoculation of in-situ oxidation process.Results show that MgO and MgAl_(2)O_(4) phases are primary oxide products for Mg−xAl alloys inoculated by in-situ oxidation.For pure Mg and Mg−1Al alloy,MgO is the only oxide product.MgAl_(2)O_(4) is another oxide product for Mg−xAl alloy as Al content increases to 3 wt.%.For Mg−3Al alloy,average grain size significantly decreases from 1135 to 237μm,with a high grain refining ratio of 79.1%.Both MgO and MgAl_(2)O_(4) possess nucleating potency forα-Mg grain.MgAl_(2)O_(4) exhibits a higher nucleating potency due to the lower misfit withα-Mg.The grain refinement of Mg−xAl alloys inoculated by in-situ oxidation process is attributed to heterogeneous nucleation events ofα-Mg grains on MgO or MgAl_(2)O_(4) particles.

利用氧化夹杂诱发异质形核是实现晶粒细化的有效途径。本研究通过原位氧化工艺实现Mg−Al二元合金的晶粒细化。结果表明,MgO和MgAl_(2)O_(4)是原位氧化孕育Mg−xAl合金的主要氧化产物。对于纯Mg和Mg−1Al合金,MgO是唯一的氧化产物。当Mg−xAl合金中Al含量增加到3%(质量分数)时,MgAl_(2)O_(4)是另一种氧化产物。经过原位氧化孕育,Mg−3Al合金的平均晶粒尺寸由1135μm显著减小至237μm,晶粒细化率高达79.1%。MgO和MgAl_(2)O_(4)都具有形核α-Mg晶粒的能力。MgAl_(2)O_(4)与α-Mg的错配度更小,表现出更高的形核能力。原位氧化工艺孕育细化Mg−xAl合金归因于α-Mg晶粒在MgO或MgAl_(2)O_(4)颗粒上的异质形核。