Balancing the strength and ductility of Mg-6Zn-0.2Ca alloy via sub-rapid solidification combined with hard-plate rolling.

Autor: Jin, Zhong-Zheng, Zha, Min, Jia, Hai-Long, Ma, Pin-Kui, Wang, Si-Qing, Liang, Jia-Wei, Wang, Hui-Yuan
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Zdroj: Journal of Materials Science & Technology; Aug2021, Vol. 81, p219-228, 10p
Abstrakt: [Display omitted] • SRS combined with HPR allows for a Mg-6Zn-0.2Ca alloy having a superior combination of ductility and strength. • Refined and dispersed eutectic phase introduced by SRS and HPR could effectively alleviate or avoid the crack initiation. • Excessive Ca solute atoms in α-Mg matrix result in the yield point phenomenon and enhanced strain-hardening ability. In this study, we successfully prepared a Mg-6Zn-0.2Ca alloy by utilizing sub-rapid solidification (SRS) combined with hard-plate rolling (HPR), whose elongation-to-failure increases from ∼17 % to ∼23 % without sacrificing tensile strength (∼290 MPa) compared with its counterpart processed via conventional solidification (CS) followed by HPR. Notably, both samples feature a similar refined grain structure with an average grain size of ∼2.1 and ∼2.5 μm, respectively. However, the high cooling rate of ∼150 K/s introduced by SRS modified both the size and morphology of Ca 2 Mg 6 Zn 3 eutectic phase in comparison to those coarse ones under CS condition. By subsequent HPR, the Ca 2 Mg 6 Zn 3 phase was further refined and dispersed uniformly by severe fragmentation. Specially, the achieved supersaturation containing excessive Ca solute atoms due to high cooling rate was maintained in the SRS-HPR condition. The mechanisms that govern the high ductility of the SRS-HPR sample could be ascribed to following reasons. First, refined Ca 2 Mg 6 Zn 3 eutectic phase could effectively alleviate or avoid the crack initiation. Furthermore, excessive Ca solute atoms in α-Mg matrix result in the yield point phenomenon and enhanced strain-hardening ability during tension. The findings proposed a short-processed strategy towards superior performance of Mg-6Zn-0.2Ca alloy for industrial applications. [ABSTRACT FROM AUTHOR]
Databáze: Supplemental Index
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