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Formation of Fine Spheroidal Microstructure of Semi-Solid AleZneMgeCu Alloy by Hyperthermally and Subsequent Isothermally Reheating

Gang Chen1), Jufu Jiang1), Zhiming Du1), Qi Cao1), Hongwei Li2,3), Xin Zhang2,3)   

  1. 1) School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
    2) Technology Institute, Beijing North Vehicle Group Corporation, Beijing 100072, China
    3) Beijing Engineering Research Center for Advanced Manufacturing and Elevation of Special Vehicle Parts, Beijing 100072, China
  • Received:2012-02-22 Revised:2012-04-22 Online:2013-10-30 Published:2013-10-16
  • Contact: G. Chen,Z. Du
  • Supported by:

    National Natural Science Foundation of China under Grant Nos. 50774026, 50875059 and 51174064.

Abstract:

The high strength 7xxx series aluminium alloys are usually difficult to be prepared as semi-solid feedstock, because some dispersoid particles (soluble only in liquid) could pin at grain and subgrain boundary to make the alloy difficultly recrystallise. In this work, a novel multistep reheating regime is developed for recrystallisation and partial melting (RAP) route to prepare fine spheroidal microstructure of semi-solid Al–Zn–Mg–Cu alloy. After reheating to 665 °C, holding for 4 min and subsequent isothermally holding at 620 °C with total heating time of 15 min, fine spheroidal microstructures with grain size of ∼40 μm were prepared without remained unrecrystallised grains and directionality, which are much finer than the conventionally obtained microstructures (∼100 μm).

Key words: AleZneMgeCu alloys, Microstructure, Semisolid, Recrystallization