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Title: Microstructure and mechanical properties of Mg-Zn-(Y/Gd) alloys
Author: Jing, Wu
ISNI:       0000 0004 5994 759X
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2016
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As-cast Mg\(_9\)\(_4\)Zn\(_2\)Y\(_4\) alloy has been subjected to compression and equal channel angular pressing (ECAP) separately. The as-cast alloy contains mainly a long-period stacking ordered (LPSO) phase and a Mg\(_2\)\(_4\)Y\(_5\) phase as secondary phases. During compression, kinking occurs in the LPSO phase and LPSO/Mg mixture. Most kink boundaries of LPSO are composed of basal < a > type dislocations. The rotation axes of the kink boundaries in LPSO/Mg are preferentially located in the (0001) plane. ECAP processing develops a bimodal microstructure consisting of large deformed grains and sub-micron dynamically recrystallised (DRXed) grains. The DRXed grains are mainly located along the original grain boundaries. Kink boundaries also acts as DRX nucleation sites. The ECAP processing increased significantly the strength of the alloy. In the as-cast Mg-Zn-Y alloys, the main secondary phase changes when different ratios of Zn/Y are applied: LPSO (Zn/Y ratio is 0.5) → LPSO+W (Zn/Y ratio is 1, W is Mg\(_3\)Zn\(_3\)Y\(_2\)) → W (Zn/Y ratio is 2.33). When Y is half replaced by Gd, the types of phases are similar. When Y is replaced fully by Gd, W phase becomes the main secondary phase. The structure of the LPSO also changes with different Zn/Y ratios and the presence of Y or Gd.
Supervisor: Not available Sponsor: University of Birmingham ; China Scholarship Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry ; TN Mining engineering. Metallurgy