Grain refining mechanism of Al-containing Mg alloys with the addition of Mn–Al alloys

• Published in: Journal of alloys and compounds Vol. 507; no. 2; pp. 410 - 413
• Main Authors: Qin, Gaowu W., Ren, Yuping, Huang, Wei, Li, Song, Pei, Wenli
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 08.10.2010; Elsevier
• Subjects: Alloys; Aluminum; Aluminum base alloys; Applied sciences; Exact sciences and technology; Foundry engineering; Grain refinement; Grain size; Magnesium alloy; Magnesium base alloys; Manganese; Manganese base alloys; Metals. Metallurgy; Mn–Al master alloys; Other casting methods. Solidification; Production techniques; ɛ-AlMn phase; Mn–Al master alloys; Grain refinement; Magnesium alloy; ɛ-AlMn phase; Grain size; Casting; Magnesium base alloys; Optical microscopy; Holding time; X ray diffraction; Mn-Al master alloys; ε-AlMn phase
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.07.164

[Display omitted] The ɛ-AlMn phase acts as the heterogeneous nucleus of α-Mg phase during the solidification of the AZ31 Mg alloy, not the γ-Al 8Mn 5 phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn–28Al alloy (pure ɛ-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 °C. The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn–Al alloys composed of either pure ɛ-AlMn, γ 2-Al 8Mn 5 or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the ɛ-AlMn phase in the Mn–Al alloys, not the γ 2-Al 8Mn 5 phase. The grain size of AZ31 Mg alloy is about 91 μm without any addition of Mn–Al alloys, but remarkably decreases to ∼55 μm with the addition of either Mn–34 wt% Al or Mn–28 wt% Al. With a minor addition of 0.5 wt% Mn–28Al alloy, the grain size of AZ31 alloy decreases to ∼53 μm, and the Mn–28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 °C.