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

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

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.

Figures/Tables 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%.

[1]	B.N. Du, Z.Y. Hu, L.Y. Sheng, D.K. Xu, Y.X. Qiao, B.J. Wang, J. Wang, Y.F. Zheng, T.F. Xi. Microstructural characteristics and mechanical properties of the hot extruded Mg-Zn-Y-Nd alloys [J]. J. Mater. Sci. Technol., 2021, 60(0): 44-55.
[2]	Dan Liu, Daoxin Liu, Mario Guagliano, Xingchen Xu, Kaifa Fan, Sara Bagherifard. Contribution of ultrasonic surface rolling process to the fatigue properties of TB8 alloy with body-centered cubic structure [J]. J. Mater. Sci. Technol., 2021, 61(0): 63-74.
[3]	Yanhua Zeng, Fenfen Yang, Zongning Chen, Enyu Guo, Minqiang Gao, Xuejian Wang, Huijun Kang, Tongmin Wang. Enhancing mechanical properties and corrosion resistance of nickel-aluminum bronze via hot rolling process [J]. J. Mater. Sci. Technol., 2021, 61(0): 186-196.
[4]	Yuan Zhong, Leifeng Liu, Ji Zou, Xiaodong Li, Daqing Cui, Zhijian Shen. Oxide dispersion strengthened stainless steel 316L with superior strength and ductility by selective laser melting [J]. J. Mater. Sci. Technol., 2020, 42(0): 97-105.
[5]	Ruifeng Dong, Jinshan Li, Hongchao Kou, Jiangkun Fan, Yuhong Zhao, Hua Hou, Li Wu. ω-Assisted refinement of α phase and its effect on the tensile properties of a near β titanium alloy [J]. J. Mater. Sci. Technol., 2020, 44(0): 24-30.
[6]	Juan Hou, Wei Chen, Zhuoer Chen, Kai Zhang, Aijun Huang. Microstructure, tensile properties and mechanical anisotropy of selective laser melted 304L stainless steel [J]. J. Mater. Sci. Technol., 2020, 48(0): 63-71.
[7]	Biwu Zhu, Xiao Liu, Chao Xie, Jing Su, Pengcheng Guo, Changping Tang, Wenhui Liu. Unveiling the underlying mechanism of forming edge cracks upon high strain-rate rolling of magnesium alloy [J]. J. Mater. Sci. Technol., 2020, 50(0): 59-65.
[8]	T. Zhang, H.W. Deng, Z.M. Xie, R. Liu, J.F. Yang, C.S. Liu, X.P. Wang, Q.F. Fang, Y. Xiong. Recent progresses on designing and manufacturing of bulk refractory alloys with high performances based on controlling interfaces [J]. J. Mater. Sci. Technol., 2020, 52(0): 29-62.
[9]	Pengfei Zhang, Yunchang Xin, Ling Zhang, Shiwei Pan, Qing Liu. On the texture memory effect of a cross-rolled Mg-2Zn-2Gd plate after unidirectional rolling [J]. J. Mater. Sci. Technol., 2020, 41(0): 98-104.
[10]	Bassem Barkia, Pascal Aubry, Paul Haghi-Ashtiani, Thierry Auger, Lionel Gosmain, Frédéric Schuster, Hicham Maskrot. On the origin of the high tensile strength and ductility of additively manufactured 316L stainless steel: Multiscale investigation [J]. J. Mater. Sci. Technol., 2020, 41(0): 209-218.
[11]	Qiuju Zheng, Lili Zhang, Hongxiang Jiang, Jiuzhou Zhao, Jie He. Effect mechanisms of micro-alloying element La on microstructure and mechanical properties of hypoeutectic Al-Si alloys [J]. J. Mater. Sci. Technol., 2020, 47(0): 142-151.
[12]	Feng Zhong, Huajie Wu, Yunlei Jiao, Ruizhi Wu, Jinghuai Zhang, Legan Hou, Milin Zhang. Effect of Y and Ce on the microstructure, mechanical properties and anisotropy of as-rolled Mg-8Li-1Al alloy [J]. J. Mater. Sci. Technol., 2020, 39(0): 124-134.
[13]	Chao Cai, Xu Wu, Wan Liu, Wei Zhu, Hui Chen, Jasper Chua Dong Qiu, Chen-Nan Sun, Jie Liu, Qingsong Wei, Yusheng Shi. Selective laser melting of near-α titanium alloy Ti-6Al-2Zr-1Mo-1V: Parameter optimization, heat treatment and mechanical performance [J]. J. Mater. Sci. Technol., 2020, 57(0): 51-64.
[14]	Wei Chen, Hande Wang, Y.C. Lin, Xiaoyong Zhang, Chao Chen, Yaping Lv, Kechao Zhou. The dynamic responses of lamellar and equiaxed near β-Ti alloys subjected to multi-pass cross rolling [J]. J. Mater. Sci. Technol., 2020, 43(0): 220-229.
[15]	S.G. Wang, M. Sun, S.Y. Liu, X. Liu, Y.H. Xu, C.B. Gong, K. Long, Z.D. Zhang. Synchronous optimization of strengths, ductility and corrosion resistances of bulk nanocrystalline 304 stainless steel [J]. J. Mater. Sci. Technol., 2020, 37(0): 161-172.