Development of low-alloyed and rare-earth-free magnesium alloys having ultra-high strength

CORC > 金属研究所 > 中国科学院金属研究所

	Development of low-alloyed and rare-earth-free magnesium alloys having ultra-high strength
	Pan, HC; Qin, GW; Huang, YM; Ren, YP; Sha, XC; Han, XD; Liu, ZQ; Li, CF; Wu, XL; Chen, HW
刊名	ACTA MATERIALIA
	2018-05-01
卷号	149 页码:350-363
关键词	Slow-speed Extrusion Zn-zr Alloy Ca-mn Alloy Mechanical-properties Low-temperature Grain-refinement Microstructure Evolution Mg-3al-1zn Alloy Prismatic-slip Pure Magnesium
ISSN号	1359-6454
英文摘要	Developing ultra-high strength in rare-earth-free Mg alloys using conventional extrusion process is a great challenge. What is even more difficult is to achieve such a goal at a lower processing cost. In this work, we report a novel low-alloyed Mg-2Sn-2Ca alloy (in wt. %) that exhibits tunable ultra-high tensile yield strength (360-440 MPa) depending on extrusion parameters. More importantly, there is little drop in mechanical properties of this alloy even when it is extruded at a speed several times higher than those used in the reported high strength Mg alloys. Examination of as-extruded microstructures of this Ca-containing Mg alloy reveals that the ultra-high strength is mainly associated with the presence of surprisingly submicron matrix grains (down to similar to 0.32 mu m). The results suggest that the Ca addition promotes accumulations of the pyramidal dislocations, which eventually transform into the low angular grain boundaries (LAGBs). The high number density of LAGBs separate the alpha-Mg matrix via either discontinuous dynamic recrystallization (DDRX) mechanism in the early stage or the continuous dynamic recrystallization (CDRX) mechanism in the later stage of extrusion, which effectively enhances the nucleation rates of the DRXed grains. More importantly, large amount of Ca segregation along LAGBs, accompanied with dynamically precipitated Mg2Ca nano-phases, are detected in the present non-severely deformed samples. It is the combination of solute segregations and numerous Mg2Ca nano-precipitates that contributes to the formation of the ultra-fine grains via pinning mechanism. The ultrafine grains size, Ca enrichment in most LAGBs, and residual Mg2Ca nano-precipitates would in turn contribute significantly to the enhancement of the yield strength of the as-extruded Mg-2Sn-2Ca (wt.%) alloy. The low content of alloying elements and the fast one-step extrusion process render the present alloys low-cost and thus have great potential in large-scale industry applications. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.; Developing ultra-high strength in rare-earth-free Mg alloys using conventional extrusion process is a great challenge. What is even more difficult is to achieve such a goal at a lower processing cost. In this work, we report a novel low-alloyed Mg-2Sn-2Ca alloy (in wt. %) that exhibits tunable ultra-high tensile yield strength (360-440 MPa) depending on extrusion parameters. More importantly, there is little drop in mechanical properties of this alloy even when it is extruded at a speed several times higher than those used in the reported high strength Mg alloys. Examination of as-extruded microstructures of this Ca-containing Mg alloy reveals that the ultra-high strength is mainly associated with the presence of surprisingly submicron matrix grains (down to similar to 0.32 mu m). The results suggest that the Ca addition promotes accumulations of the pyramidal dislocations, which eventually transform into the low angular grain boundaries (LAGBs). The high number density of LAGBs separate the alpha-Mg matrix via either discontinuous dynamic recrystallization (DDRX) mechanism in the early stage or the continuous dynamic recrystallization (CDRX) mechanism in the later stage of extrusion, which effectively enhances the nucleation rates of the DRXed grains. More importantly, large amount of Ca segregation along LAGBs, accompanied with dynamically precipitated Mg2Ca nano-phases, are detected in the present non-severely deformed samples. It is the combination of solute segregations and numerous Mg2Ca nano-precipitates that contributes to the formation of the ultra-fine grains via pinning mechanism. The ultrafine grains size, Ca enrichment in most LAGBs, and residual Mg2Ca nano-precipitates would in turn contribute significantly to the enhancement of the yield strength of the as-extruded Mg-2Sn-2Ca (wt.%) alloy. The low content of alloying elements and the fast one-step extrusion process render the present alloys low-cost and thus have great potential in large-scale industry applications. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
学科主题	Materials Science, Multidisciplinary ; Metallurgy & Metallurgical Engineering
语种	英语
资助机构	National Key Research and Development Program of China [2016YFB0701200]; National Natural Science Foundation of China [51525101, U1610253, 51371046, 51501032, 51131009]
公开日期	2018-06-05
内容类型	期刊论文
源URL	[http://ir.imr.ac.cn/handle/321006/79327]
专题	金属研究所_中国科学院金属研究所
通讯作者	Qin, GW (reprint author), Northeastern Univ, Minist Educ, Sch Mat Sci & Engn, Key Lab Anisotropy & Texture Mat, Shenyang 110819, Liaoning, Peoples R China.; Nie, JF (reprint author), Chongqing Univ, Sch Mat Sci & Engn, Chongqing 400044, Peoples R China.; Wang, YZ (reprint author), Ohio State Univ, Dept Mat Sci & Engn, 2041 N Coll Rd, Columbus, OH 43210 USA.
推荐引用方式 GB/T 7714	Pan, HC,Qin, GW,Huang, YM,et al. Development of low-alloyed and rare-earth-free magnesium alloys having ultra-high strength[J]. ACTA MATERIALIA,2018,149:350-363.
APA	Pan, HC.,Qin, GW.,Huang, YM.,Ren, YP.,Sha, XC.,...&Wang, YZ .(2018).Development of low-alloyed and rare-earth-free magnesium alloys having ultra-high strength.ACTA MATERIALIA,149,350-363.
MLA	Pan, HC,et al."Development of low-alloyed and rare-earth-free magnesium alloys having ultra-high strength".ACTA MATERIALIA 149(2018):350-363.