Effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy

doi:10.1016/j.jmst.2018.05.002

材料科学与技术 ›› 2018, Vol. 34 ›› Issue (12): 2256-2262.DOI: 10.1016/j.jmst.2018.05.002

收稿日期:2017-11-01 修回日期:2018-01-09 接受日期:2018-02-06 出版日期:2018-12-20 发布日期:2018-11-15

Effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy

Wencai Liu^a, Shi Feng^a^*(), Zhongquan Li^b, Jiong Zhao^a, Guohua Wu^a^*(), Xianfei Wang^b, Lv Xiao^b, Wenjiang Ding^a

a National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composite, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
b Shanghai Spaceflight Precision Machinery Institute, Shanghai 201600, China

Received:2017-11-01 Revised:2018-01-09 Accepted:2018-02-06 Online:2018-12-20 Published:2018-11-15
Contact: Feng Shi,Wu Guohua

摘要/Abstract

Abstract:

This study was conducted to discuss the effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5Y (wt%) alloy, which was prepared by casting, and then homogenized and rolled at 200?°C. The rolling process was conducted with 10% reduction per pass and five different accumulated strains, varying from 10% to 70%. The results indicate that the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloys are composed of α-Mg, β-Li, AlLi and Al₂Y phases. After rolling process, anisotropic microstructure was observed. α-Mg phase got elongated in both rolling direction and transverse direction with the addition of rolling strain. Consequently, the strength of the alloy in both directions was notably improved whereas the elongation declined, mainly caused by strain hardening and dispersion strengthening. The tensile properties of the as-rolled alloys in the RD, no matter the YS, UTS or the elongation, are higher than those of the TD due to their larger deformation strain and significant anisotropy in the hcp α-Mg phase. In addition, the fracture and strengthening mechanism of the tested alloys were also investigated systematically.

Key words: Mg-8Li-3Al-2Zn-0.5Y, Rolling, Anisotropy, Tensile properties, Strain hardening

. [J]. 材料科学与技术, 2018, 34(12): 2256-2262.

Wencai Liu, Shi Feng, Zhongquan Li, Jiong Zhao, Guohua Wu, Xianfei Wang, Lv Xiao, Wenjiang Ding. Effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy[J]. J. Mater. Sci. Technol., 2018, 34(12): 2256-2262.

图/表 10

Fig. 1. Size and directions of the sheets for rolling processing.

Table 1 Chemical composition (wt%) of the studied alloy Mg-8Li-3Al-2Zn-0.5Y.

Li	Al	Zn	Y	Mg
8.11	2.98	2.12	0.44	Bal.

Fig. 2. 3-Dimensional optical micrographs of the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloy with different rolling strains: (a) as-cast, (b) 10%, (c) 30%, (d) 50%, (e) 60%, (f) 70%.

Fig. 3. XRD patterns of the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloy with different rolling strains: (a) as-cast, (b) 10%, (c) 30%, (d) 50%, (e) 60%, (f) 70%.

Fig. 4. SEM micrographs of the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloy with different rolling strains: (a) as-cast, (b) 10% (c) 30%, (d) 50%, (e) 60%, (f) 70%.

Fig. 5. EDS analysis of the labeled-A precipitate in Fig. 4(a).

Fig. 6. Tensile properties of the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloy with different rolling strains along the RD and the TD.

Table 2 Tensile properties of the as-cast and as-rolled alloys in 2 directions.

Direction	Rolling strain	YS (MPa)		UTS (MPa)		Elongation (%)
		Mean	STD	Mean	STD	Mean	STD
As-cast		165.1	5.6	200.3	4.2	13.9	2.6
RD	10%	169.2	4.1	209.3	3.7	10.5	1.2
	30%	205.3	3.5	240.2	4.5	8.2	1.2
	50%	213.5	4.6	247.1	2.7	7.3	1.1
	60%	224.8	4.4	247.5	1.6	7.2	0.5
	70%	230.3	2.1	250.9	3.1	7.1	0.9
TD	10%	181.3	2.3	211.3	1.5	7.5	0.9
	30%	198.6	2.8	228.7	4.6	4.3	0.6
	50%	202.6	2.2	238.2	3.3	3.2	0.5
	60%	208.8	3.8	239.7	3.2	2.9	0.3
	70%	210.4	4.2	248.2	2.5	2.7	0.2

Fig. 7. Microstructure of fracture surface of the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloy with different rolling strains vertical to the RD: (a) as-cast, (b) 10%, (c) 30%, (d) 50%, (e) 60%, (f) 70%.

Fig. 8. Microstructure of fracture surface of the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloy with different rolling strains vertical to the TD: (a) as-cast, (b) 10%, (c) 30%, (d) 50%, (e) 60%, (f) 70%.

Effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy

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