Exploring the Hall-Petch relation and strengthening mechanism of bimodal-grained Mg–Al–Zn alloys

• Published in: Journal of alloys and compounds Vol. 833; p. 155004
• Main Authors: Jin, Zhong-Zheng, Zha, Min, Yu, Zhi-Yuan, Ma, Pin-Kui, Li, Yong-Kang, Liu, Jin-Ming, Jia, Hai-Long, Wang, Hui-Yuan
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.08.2020; Elsevier BV
• Subjects: Aluminum base alloys; Bimodal grain structure; Deformation effects; Grains; Hall-petch relation; Magnesium base alloys; Mg–Al–Zn alloys; Slip; Strengthening mechanism; Twinning; Yield strength; Yield stress; Zinc; Mg–Al–Zn alloys; Bimodal grain structure; Hall-petch relation; Strengthening mechanism
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.155004

The Hall-Petch (H–P) relation for bimodal-grained Mg–Al–Zn alloys consisting of both ultra-fine grains (UFGs)/fine grains (FGs) and coarse grains (CGs) is discussed separately for yield stress and flow stress according to different deformation behaviors of UFGs/FGs and CGs. The yield behavior is controlled by basal dislocation slip of UFGs/FGs and twinning of CGs collectively. Thereafter, non-basal slip is activated in basal-oriented CGs as deformation proceeds. Considering the synergy effect of UFGs/FGs and CGs, we present modified H–P relations for bimodal-grained Mg–3Al–1Zn (AZ31) and Mg–9Al–1Zn (AZ91) alloys containing either few or numerous dispersed particles, respectively, by which the calculated strengths depict experimental values well. [Display omitted] •The strengthening mechanism and deformation behavior of bimodal-grained Mg alloys are discussed.•The yield behavior is controlled by basal slip and twinning collectively, followed by non-basal slip in basal-oriented CGs.•A quantitative Hall-Petch relation is built to predict the yield strength of bimodal-grained AZ31 and AZ91 alloys.