Acta Metallurgica Sinica (English Letters) ›› 2013, Vol. 26 ›› Issue (4): 447-454.DOI: 10.1007/s40195-012-0261-7

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Microstructure Formation Mechanism During a Novel Semisolid Rheo-rolling Process of AZ91 Magnesium Alloy

Zhanyong ZHAO, Renguo GUAN, Xiang WANG, Chunming LIU   

  1. College of Materials and Metallurgy,Northeastern University, Shenyang 110189, China
  • Received:2012-12-16 Revised:2013-03-28 Online:2013-08-25 Published:2013-07-11
  • Contact: Renguo GUAN
  • Supported by:

    National Natural Science Foundation for Outstanding Young Scholars of China (No. 51222405), National Natural Science Foundation of China (No. 51034002), the Fok
    Ying Tong Education Foundation (No.132002), the Basic Scientific Research Operation of Center University (Nos. N120602002 and N120502001) and Chinese National Program for Fundamental Research and Development (No. 2011CB610405).

Abstract:

A novel semisolid rheo-rolling process of AZ91 alloy was proposed. The microstructure formation mechanism of AZ91 magnesium alloy during the process was studied. The results reveal that the eruptive nucleation and the heterogeneous nucleation exist. During the grain growth process, the grain breakage took place and transformed into fine spherical or rosette grains on the sloping plate gradually, the other grain growth style is direct globular growth. Due to the secondary crystallization of the remnant liquids in the roll gap, the microstructure of the strip becomes finer with the increment of the casting temperature from 650℃ to 690℃. But when the casting temperature reached 710℃, a part of the liquid alloy transformed into the eutectic phases, and the primary grains ripened to form coarse dendrites. In the casting temperature range from 650℃ to 690℃, AZ91 alloy strip with fine spherical or rosette grains was prepared by the proposed process.

Key words: Semisolid, Rolling, AZ91 alloy, Microstructure