Research Progress and Future Prospect on New Low-Alloyed Bake-Hardenable Magnesium Alloys
WANG Huiyuan1,2,3(), MENG Zhaoyuan1,3, JIA Hailong1,3, XU Xinyu4(), HUA Zhenming2
1 Key Laboratory of Automobile Materials of Ministry of Education, School of Materials Science and Engineering, Jilin University, Changchun 130025, China 2 School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China 3 International Center of Future Science, Jilin University, Changchun 130012, China 4 Department of Mechanical Engineering, The University of Hong Kong, Hong Kong 999077, China
Cite this article:
WANG Huiyuan, MENG Zhaoyuan, JIA Hailong, XU Xinyu, HUA Zhenming. Research Progress and Future Prospect on New Low-Alloyed Bake-Hardenable Magnesium Alloys. Acta Metall Sin, 2025, 61(3): 372-382.
Magnesium alloys are widely used in aerospace, automotive, and rail transit industries as the lightest structural metallic materials. Minor alloying additions have proven to be effective in enhancing processability and ductility. Recent studies demonstrate that low-alloyed Mg-Zn-Ca(-Al) alloys exhibit exceptional room-temperature formability due to their weak texture after rolling and annealing. This advancement indicates that magnesium alloy sheets could potentially replace steel and aluminum alloy in body panel applications. However, achieving improved strength while maintaining formability remains a substantial challenge, limiting the broader adoption of low-alloyed magnesium alloys. Bake hardening (BH) treatment, a technique commonly employed for steel and Al body panels to enhance post-forming strength, has recently been shown to strengthen Mg-Zn-Ca(-Al) alloy sheets. BH treatment partially addresses the trade-off between formability and strength in low-alloyed magnesium alloys by utilizing the limited solid solution atoms. As the development of BH magnesium alloy sheets progresses, further improvements in properties or the design of new alloy compositions require a thorough understanding of the relationship between microstructure and mechanical properties and the underlying mechanisms. This review examines recent advancements in low-alloyed bake-hardenable magnesium alloys, focusing on three mechanisms: dislocation segregation, twin boundary segregation, and Guinier-Preston (GP) zone-induced bake hardening. Additionally, it provides a brief outlook on the future development trends aimed at expanding the application range of these materials. The insights presented here are expected to guide the design and optimization of BH magnesium alloys with enhanced performance and broader industrial applicability.
Fig.1 Correlative TEM-APT characterization of 2% pre-strained and bake-hardened (BH) AZMX1110 alloys[15] (APT—atom probe tomography, insets in Figs.1a and d are the selected area electron diffraction (SAED) patterns) (a) two-beam bright field-TEM (BF-TEM) image of 2% pre-strained sample obtained under the g = ( g —diffraction vector) (b) APT map obtained from the same tip shown in Fig.1a (c) overlay of Fig.1b and the corresponding region in Fig.1a (d) two-beam BF-TEM image of bake-hardened sample obtained under the g = (e) APT map obtained from the same tip shown in Fig.1d (a-d represents four dislocations) (f) overlay of Fig.1e and the corresponding region in Fig.1d
Fig.2 Tensile engineering stress-strain curves of annealed, directly aged, pre-strained, and bake-hardened ZXTM1000 alloys (a) and tensile yield strength as function of elongation for various rolled and extruded Mg alloys (b)[31]
Alloy
Processing
YS
MPa
UTS
MPa
EL
%
BH mechanism
Ref.
Mg-1.0Zn-0.45Ca-0.33Sn-0.2Mn
Annealed
265
291
24.6
Solute segregation at dislocations
[31]
BH
297
301
21.9
Mg-2.0Zn-0.5Ca
T4
95
208
12.0
Solute segregation at dislocations
and twin boundaries
[32]
BH
200
244
17.0
Mg-1.61Zn-0.57Mn-0.54Ca-0.46Al
T4
234
288
21.1
GP zone strengthening
[33]
BH
293
316
19.2
AA6016 Al alloy
PA
122
234
27.8
Mg-Si cluster strengthening
[34]
BH
223
291
22.7
AA6111 Al alloy
T4
150
268
19.2 (UL)
Precipitate strengthening
[35]
PFHT
280
325
10.9 (UL)
BH
289
331
10.5 (UL)
B180H1 Steel
BH
241
352
38.0
Solute segregation at dislocations
[36]
Table 1 Mechanical properties of low-alloyed bake-hardening Mg alloys and bake-hardening steels/aluminum alloys[31-36]
Fig.3 High-angle annular dark field-scanning transmission electron microscope (HAADF-STEM) images (a-e) and EDS results (f-h) of pre-strained ZXTM1000 alloy during in situ heating[31] (White arrows in Figs.3a and e represent areas of EDS line scanning results in Fig.3h; red arrows in Fig.3e show the solute segregation at dislocations after in situ heating for 30 min) (a) pre-strained (b) reaching at 175 oC (c) heating at 175 oC for 10 min (d) 175 oC for 20 min (e) 175 oC for 30 min (f, g) EDS mappings of pre-strained (f) and after heating (g) samples (h) EDS line scanning results of white arrows in Figs.3a and e
Fig.4 Periodic segregation of solutes in twinning boundaries (TBs)[39] (a, c) HAADF-STEM images showing {} TBs in Mg-0.2Zn alloys (atomic fraction, %) (a) and {} TBs in Mg-0.8Zn alloy (atomic fraction, %) (c) (b, d) close-ups of Figs.4a and c, respectively (e, f) schematic illustrations of Figs.3b and d, respectively (Blue (in the paper plane) or purples (out of the paper plane) balls represent atoms in the A layer, yellow (in the paper plane) or orange (out of the paper plane) balls represent atoms in the B layer)
Fig.5 TEM analyses of the bake-hardened Mg-2.0Zn-0.5Ca alloy[32] (a, e) BF-TEM images of twin boundary, taken from the [] direction (a) and dislocations (e) (Insets are the corresponding SAED patterns at the white crosshair; M and T represent matrix and twinning, respectively) (b, f) HAADF-STEM images of the white rectangle region in Fig.5a (b) and dislocations (f) (c, d) EDS mappings of the white rectangle region in Fig.5b (g) line EDS scanning result of the white line in Fig.5f
Fig.6 TEM and APT analyses and mechanical properties of the Mg-1.61Zn-0.57Mn-0.54Ca-0.46Al (ZMXA2110) alloy[33] (a) electron backscattered diffraction (EBSD) image of ZMXA2110 alloy under solution treatment at 450 oC for 10 min (Inset is the distribution of grain size. RD—rolling direction, TD—transverse direction) (b) strain-stress curves of solution treated and bake-hardened ZMXA2110 alloy (Inset is the Erichsen cupping test result of the solution treated ZMXA2110 alloy. IE—index Erichsen) (c) tensile yield strength and IE value of ZMXA2110 alloy and other Mg sheet alloys (d-f) TEM (d) and high resolution TEM (HRTEM) (f) images and SAED (e) pattern of bake-hardened ZMXA2110 sample which were obtain along the [100]Mg zone axis (g-i) atom maps (g), APT map of Mg and iso-concentration surface of 1.0%Ca (atomic fraction) (in cyan) (h), and concentration proxigram histogram corresponding to the iso-concentration surface in Fig.6h (i)
1
Wang H Y, Zhang H, Xu X Y, et al. Current research and future prospect on microstructure stability of superplastic light alloys [J]. Acta Metall. Sin., 2018, 54: 1618
doi: 10.11900/0412.1961.2018.00391
Wang H Y, Xia N, Bu R Y, et al. Current research and future prospect on low-alloyed high-performance wrought magnesium alloys [J]. Acta Metall. Sin., 2021, 57: 1429
doi: 10.11900/0412.1961.2021.00347
Liu Y, Zeng G, Liu H, et al. Grain refinement mechanism and research progress of magnesium alloy incorporating Zr [J]. Acta Metall. Sin., 2024, 60: 129
doi: 10.11900/0412.1961.2023.00241
Shen Z, Wang Z P, Hu B, et al. Research progress on the mechanisms controlling high-temperature oxidation resistance of Mg alloys [J]. Acta Metall. Sin., 2023, 59: 371
doi: 10.11900/0412.1961.2022.00495
Li J R, Xie D S, Zhang D D, et al. Microstructure evolution mechanism of new low-alloyed high-strength Mg-0.2Ce-0.2Ca alloy during extrusion [J]. Acta Metall. Sin., 2023, 59: 1087
Zhu G J, Wang S Q, Zha M, et al. Effect of rare earth element Ce on the bulk texture and mechanical anisotropy of as-extruded Mg-0.3Al-0.2Ca-0.5Mn alloy sheets [J]. Acta Metall. Sin., 2024, 60: 1079
Zeng Z R, Stanford N, Davies C H J, et al. Magnesium extrusion alloys: A review of developments and prospects [J]. Int. Mater. Rev., 2019, 64: 27
doi: 10.1080/09506608.2017.1421439
8
Wang S Q, Zha M, Jia H L, et al. A review of superplastic magnesium alloys: Focusing on alloying strategy, grain structure control and deformation mechanisms [J]. J. Mater. Sci. Technol., 2025, 211: 303
doi: 10.1016/j.jmst.2024.06.002
9
Zhao L Q, Wang C, Chen J C, et al. Development of weak-textured and high-performance Mg-Zn-Ca alloy sheets based on Zn content optimization [J]. J. Alloys Compd., 2020, 849: 156640
10
Xia N, Wang C, Gao Y P, et al. Enhanced ductility of Mg-1Zn-0.2Zr alloy with dilute Ca addition achieved by activation of non-basal slip and twinning [J]. Mater. Sci. Eng., 2021, A813: 141128
11
Liu S, Wang C, Ning H, et al. Achieving high ductility and low in-plane anisotropy in magnesium alloy through a novel texture design strategy [J]. J. Magnesium Alloy., 2024, 12: 2863
12
Zeng Z R, Zhu Y M, Xu S W, et al. Texture evolution during static recrystallization of cold-rolled magnesium alloys [J]. Acta Mater., 2016, 105: 479
13
Bian M Z, Sasaki T T, Suh B C, et al. A heat-treatable Mg-Al-Ca-Mn-Zn sheet alloy with good room temperature formability [J]. Scr. Mater., 2017, 138: 151
14
Trang T T T, Zhang J H, Kim J H, et al. Designing a magnesium alloy with high strength and high formability [J]. Nat. Commun., 2018, 9: 2522
doi: 10.1038/s41467-018-04981-4
pmid: 29955065
15
Bian M Z, Sasaki T T, Nakata T, et al. Bake-hardenable Mg-Al-Zn-Mn-Ca sheet alloy processed by twin-roll casting [J]. Acta Mater., 2018, 158: 278
16
Tang H. Automotive Vehicle Assembly Processes and Operations Management [M]. Warrendale: SAE International, 2017: 135
17
Shome M, Tumuluru M. Welding and Joining of Advanced High Strength Steels (AHSS) [M]. Cambridge: Woodhead Publishing, 2015: 23
18
Rana R, Singh S B. Automotive Steels: Design, Metallurgy, Processing and Applications [M]. Amsterdam: Elsevier, 2017: 260
19
Cottrell A H, Bilby B A. Dislocation theory of yielding and strain ageing of Iron [J]. Proc. Phys. Soc., 1949, 62A: 49
20
Blavette D, Cadel E, Fraczkiewicz A, et al. Three-dimensional atomic-scale imaging of impurity segregation to line defects [J]. Science, 1999, 286: 2317
pmid: 10600736
21
Zhu S, Li Z H, Yan L Z, et al. Effects of Zn addition on the natural ageing behavior and bake hardening response of a pre-aged Al-Mg-Si-Cu alloy [J]. Acta Metall. Sin., 2019, 55: 1395
Wang H, Shi W, He Y L, et al. Study of Mn and P solute distributions and their effect on the tensile behavior in ultra low carbon bake hardening steels [J]. Acta Metall. Sin., 2011, 47: 263
doi: 10.3724/SP.J.1037.2010.00693
Bryant J D. The effects of preaging treatments on aging kinetics and mechanical properties in AA6111 aluminum autobody sheet [J]. Metall. Mater. Trans., 1999, 30: 1999
24
Hou Z R, Opitz T, Xiong X C, et al. Bake-partitioning in a press-hardening steel [J]. Scr. Mater., 2019, 162: 492
25
Aruga Y, Kozuka M, Takaki Y, et al. Effects of natural aging after pre-aging on clustering and bake-hardening behavior in an Al-Mg-Si alloy [J]. Scr. Mater., 2016, 116: 82
26
Soenen B, De A K, Vandeputte S, et al. Competition between grain boundary segregation and Cottrell atmosphere formation during static strain aging in ultra low carbon bake hardening steels [J]. Acta Mater., 2004, 52: 3483
27
Hu W W, Yang Z Q, Ye H Q. Cottrell atmospheres along dislocations in long-period stacking ordered phases in a Mg-Zn-Y alloy [J]. Scr. Mater., 2016, 117: 77
28
Xiao L R, Chen X F, Cao Y, et al. Solute segregation assisted nanocrystallization of a cold-rolled Mg-Ag alloy during annealing [J]. Scr. Mater., 2020, 177: 69
29
Xiao L R, Chen X F, Wei K, et al. Effect of dislocation configuration on Ag segregation in subgrain boundary of a Mg-Ag alloy [J]. Scr. Mater., 2021, 191: 219
30
Hua Z M, Li M X, Wang C, et al. Pre-strain mediated fast natural aging in a dilute Mg-Zn-Ca-Sn-Mn alloy [J]. Scr. Mater., 2021, 200: 113924
31
Hua Z M, Zha M, Meng Z Y, et al. Rapid dislocation-mediated solute repartitioning towards strain-aging hardening in a fine-grained dilute magnesium alloy [J]. Mater. Res. Lett., 2022, 10: 21
32
Li Y J, Fang Y, Wang C, et al. Enhanced strength-ductility synergy achieved through twin boundary pinning in a bake-hardened Mg-2Zn-0.5Ca alloy [J]. Mater. Sci. Eng., 2022, A831: 142239
33
Meng Z Y, Wang C, Hua Z M, et al. Achieving extraordinary thermal stability of fine-grained structure in a dilute magnesium alloy [J]. Mater. Res. Lett., 2022, 10: 797
34
Zhu S Q, Shih H C, Cui X Y, et al. Design of solute clustering during thermomechanical processing of AA6016 Al-Mg-Si alloy [J]. Acta Mater., 2021, 203: 116455
35
Klos A, Kellner S, Wortberg D, et al. Forming characteristics of artificial aging Al-Mg-Si-Cu sheet alloys [J]. AIP Conf. Proc., 2017, 1896: 020020
36
Tan S K, Pan X W, Li M, et al. Summary of steel sheet in Cherry Car Co. [J]. Automob. Technol. Mater., 2004, (6): 59
Yang M, Jia H L, Jiang R, et al. Excellent synergy of formability and strength of a Mg-Zn-Y-Ca-Zr alloy by tailoring segregation-assisted weak elliptical ring texture [J]. J. Magnes. Alloy., 2024, DOI: 10.1016/j.jma.2024.06.029
38
Lejček P. Grain Boundary Segregation in Metals [M]. Berlin: Springer, 2010: 25
39
Nie J F, Zhu Y M, Liu J Z, et al. Periodic segregation of solute atoms in fully coherent twin boundaries [J]. Science, 2013, 340: 957
doi: 10.1126/science.1229369
pmid: 23704567
40
He C, Li Z Q, Chen H W, et al. Unusual solute segregation phenomenon in coherent twin boundaries [J]. Nat. Commun., 2021, 12: 722
doi: 10.1038/s41467-021-21104-8
pmid: 33526770
41
Zhu Y M, Xu S W, Nie J F. $\left\{ 10\bar{1}1 \right\}$ twin boundary structures in a Mg-Gd alloy [J]. Acta Mater., 2018, 143: 1
42
Somekawa H, Watanabe H, Basha D A, et al. Effect of twin boundary segregation on damping properties in magnesium alloy [J]. Scr. Mater., 2017, 129: 35
43
Zhou X Z, Su H H, Ye H Q, et al. Removing basal-dissociated<c + a> dislocations by $\left\{ 10\bar{1}2 \right\}$ deformation twinning in magnesium alloys [J]. Acta Mater., 2021, 217: 117170
44
Wang C, Ju H, Li M X, et al. Segregation potency at $\left\{ 10\bar{1}2 \right\}$ and $\left\{ 10\bar{1}1 \right\}$ twin boundaries in Mg with Zn and Ca co-addition: A first-principles study [J]. Materialia, 2021, 15: 101031
45
Wang X, Hu Y, Yu K H, et al. Room temperature deformation-induced solute segregation and its impact on twin boundary mobility in a Mg-Y alloy [J]. Scr. Mater., 2022, 209: 114375
46
Zhang H, Li Y X, Ding Z G, et al. Origin of twin-like $\left\{ 33\bar{6}4 \right\}$ tilt boundary and associated solute segregation in a high strain rate deformed Mg-Y alloy [J]. Scr. Mater., 2021, 201: 113982
47
Su H H, Zheng S J, Yang Z Q, et al. Atomic-scale insights into grain boundary-mediated plasticity mechanisms in a magnesium alloy subjected to cyclic deformation [J]. Acta Mater., 2024, 277: 120210
48
Chen X F, Xiao L R, Ding Z G, et al. Atomic segregation at twin boundaries in a Mg-Ag alloy [J]. Scr. Mater., 2020, 178: 193
49
Somekawa H, Tsuru T, Naito K, et al. Control of twin boundary mobility by solute segregation in Mg binary alloys [J]. Scr. Mater., 2024, 249: 116173
50
Yang Q, Lv S H, Chen P, et al. Formation and solute segregation for an asymmetric tilt boundary on $\left\{ 10\bar{1}2 \right\}$ twin boundaries [J]. J. Magnes. Alloy., 2024, DOI: 10.1016/j.jma.2024.01.026
51
Li Z H, Sasaki T T, Bian M Z, et al. Role of Zn on the room temperature formability and strength in Mg-Al-Ca-Mn sheet alloys [J]. J. Alloys Compd., 2020, 847: 156347
52
Basu I, Chen M, Wheeler J, et al. Segregation-driven exceptional twin-boundary strengthening in lean Mg-Zn-Ca alloys [J]. Acta Mater., 2022, 229: 117746
53
Nie J F. Precipitation and hardening in magnesium alloys [J]. Metall. Mater. Trans., 2012, 43A: 3891
54
Lee Y S, Koh D H, Kim H W, et al. Improved bake-hardening response of Al-Zn-Mg-Cu alloy through pre-aging treatment [J]. Scr. Mater., 2018, 147: 45
55
Nie J F, Muddle B C. Precipitation hardening of Mg-Ca(-Zn) alloys [J]. Scr. Mater., 1997, 37: 1475
56
Oh-ishi K, Watanabe R, Mendis C L, et al. Age-hardening response of Mg-0.3at.%Ca alloys with different Zn contents [J]. Mater. Sci. Eng., 2009, A526: 177
57
Jayaraj J, Mendis C L, Ohkubo T, et al. Enhanced precipitation hardening of Mg-Ca alloy by Al addition [J]. Scr. Mater., 2010, 63: 831
58
Cihova M, Schäublin R, Hauser L B, et al. Rational design of a lean magnesium-based alloy with high age-hardening response [J]. Acta Mater., 2018, 158: 214
59
Nakata T, Xu C, Ajima R, et al. Strong and ductile age-hardening Mg-Al-Ca-Mn alloy that can be extruded as fast as aluminum alloys [J]. Acta Mater., 2017, 130: 261
60
Li Z H, Sasaki T T, Uedono A, et al. Role of Zn on the rapid age-hardening in Mg-Ca-Zn alloys [J]. Scr. Mater., 2022, 216: 114735
Nakata T, Xu C, Matsumoto Y, et al. Optimization of Mn content for high strengths in high-speed extruded Mg-0.3Al-0.3Ca (wt%) dilute alloy [J]. Mater. Sci. Eng., 2016, 673A: 443
63
Nakata T, Xu C, Ajima R, et al. Improving mechanical properties and yield asymmetry in high-speed extrudable Mg-1.1Al-0.24Ca (wt%) alloy by high Mn addition [J]. Mater. Sci. Eng., 2018, A712: 12
64
Bian M Z, Zeng Z R, Xu S W, et al. Improving formability of Mg-Ca-Zr sheet alloy by microalloying of Zn [J]. Adv. Eng. Mater., 2016, 18: 1763
65
Nakata T, Xu C, Yoshida Y, et al. Improving room-temperature stretch formability of a high-alloyed Mg-Al-Ca-Mn alloy sheet by a high-temperature solution-treatment [J]. Mater. Sci. Eng., 2021, A801: 140399
66
Schäublin R E, Becker M, Cihova M, et al. Precipitation in lean Mg-Zn-Ca alloys [J]. Acta Mater., 2022, 239: 118223
67
Cheng D, Hoglund E R, Wang K, et al. Atomic structures of ordered monolayer GP zones in Mg-Zn-X (X = Ca, Nd) systems [J]. Scr. Mater., 2022, 216: 114744
68
Li Z H, Cheng D, Wang K, et al. Revisited precipitation process in dilute Mg-Ca-Zn alloys [J]. Acta Mater., 2023, 257: 119072
69
Meng Z Y, Jia H L, Ju H, et al. Enhanced age-hardening in a lean Mg-Al-Ca-Mn alloy by trace silver addition [J]. Mater. Res. Lett., 2025
70
Li Z H, Sasaki T T, Shiroyama T, et al. Simultaneous achievement of high thermal conductivity, high strength and formability in Mg-Zn-Ca-Zr sheet alloy [J]. Mater. Res. Lett., 2020, 8: 335
71
Bhattacharyya J J, Sasaki T T, Nakata T, et al. Determining the strength of GP zones in Mg alloy AXM10304, both parallel and perpendicular to the zone [J]. Acta Mater., 2019, 171: 231
doi: 10.1016/j.actamat.2019.04.035
72
Bhattacharyya J J, Nakata T, Kamado S, et al. Origins of high strength and ductility combination in a Guinier-Preston zone containing Mg-Al-Ca-Mn alloy [J]. Scr. Mater., 2019, 163: 121
73
Bhattacharyya J J, Sasaki T T, Nakata T, et al. Why rolled Mg-Al-Ca-Mn alloys are less responsive to aging as compared to the extruded [J]. Scr. Mater., 2023, 233: 115513
74
Stanford N, Barnett M R. Solute strengthening of prismatic slip, basal slip and $\left\{ 10\bar{1}2 \right\}$ twinning in Mg and Mg-Zn binary alloys [J]. Int. J. Plast., 2013, 47: 165
75
Pan H C, Kang R, Li J R, et al. Mechanistic investigation of a low-alloy Mg-Ca-based extrusion alloy with high strength-ductility synergy [J]. Acta Mater., 2020, 186: 278
