Mechanoluminescence or Room-Temperature Phosphorescence: Molecular Packing-Dependent Emission Response

Article abstract of DOI:10.1002/anie.201911648

Mechanoluminescence (ML) and room-temperature photophosphorescence (RTP) were achieved in polymorphisms of a triphenylamine derivative with ortho-substitution. This molecular packing-dependent emission afforded crucial information to deeply understand the intrinsic mechanism of different emission forms and the possible packing–function relationship. With the incorporation of solid-state ¹³C NMR spectra of single crystals, as well as the analysis of crystal structures, the preferred packing modes for ML and/or RTP were investigated in detail, which can guide the reasonable design of organic molecules with special light-emission properties.

Full text of DOI:10.1002/anie.201911648

Materials Research Express
PAPER
Investigation on hot tearing behavior and its mechanism of Mg-4.5Zn-xY-
yNd(x + y = 6, x = 0, 1, 3, 6) alloys
To cite this article: Xingxing Li et al 2019 Mater. Res. Express 6 106535
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Mater. Res. Express 6 (2019) 106535
https://doi.org/10.1088/2053-1591/ab381a
PAPER
Investigation on hot tearing behavior and its mechanism of Mg-
.5Zn-xY-yNd(x+y=6, x=0, 1, 3, 6) alloys
RECEIVED
4
July 2019
4
REVISED
27 July 2019
1
1
1
1
1
2
3
Xingxing Li , Zheng Liu , Yue Wang , Ziqi Wei , Shimeng Liu , Zhenglai Zhang and Yingdong Ju
ACCEPTED FOR PUBLICATION
1
2
August 2019
College of Materials Science and Engineering, Shenyang University of Technology, Shenyang, People’s Republic of China
Zhejiang Huashuo Technology Co., Ltd, Ningbo 315802, People’s Republic of China
2
PUBLISHED
3
9
August 2019
Ningbo Haizhi Institute of Materials Industry Innovation, Ningbo 315033, People’s Republic of China
E-mail: zliu4321@126.com
Keywords: Mg-Zn-Y-Nd alloy, hot tearing susceptibility, LPSO phase, W-phase, T-phase
Abstract
The hot tearing susceptibility (HTS) and its mechanism of Mg-4.5Zn-xY-yNd (x+y=6, x=0, 1, 3,
) alloys is studied based on Clyne-Davies’ model and ‘T’ mold. The hot tearing tendency of four alloys
6
is characterized by SEM, XRD and TEM. Morever, HTS of four kinds of Mg-4.5Zn-xY-yNd alloys is
predicted by numerical simulation (ProCAST). The order of the four alloys arranged according to
HTS from high to low is as follows: Mg-4.5Zn-3Y-3Nd>Mg-4.5Zn-1Y-5Nd>Mg-4.5Zn-
6Nd>Mg-4.5Zn-6Y. The results show that the crystalline state of α-Mg phase and the type of the
second phase change with the relative contents of Y and Nd, which are the main factors determining
the hot tearing tendency. For Mg-4.5Zn-6Y alloy, the main precipitated phases are LPSO phase
(
Mg ZnY) and W phase (Mg Zn Y ). For Mg-4.5Zn-3Y-3Nd and Mg-4.5Zn-1Y-5Nd alloys, the
1
2
3
3 2
main precipitates are W phase (Mg Zn (Y, Nd) ). For Mg-4.5Zn-6Nd alloy, the main precipitation
3
3
2
phase is only T phase (Mg-Zn-Nd ternary phase).
1
. Introduction
With the shortage of global energy and resources, countries around the world are paying more attention to
environmental protection. Magnesium alloys have many advantages, such as less melting energy consumption,
faster feeding and solidification speed, shorter die casting cycle and longer service life of mold. The effect of
substituting steels, aluminium alloys and plastic parts under conventional use conditions is very excellent.
Therefore, it is known as ‘Metal of the 21st Century’ and widely used in automobile, computer, communication
and other broad fields [1–4].
Due to the low mechanical properties of commercial magnesium alloys, the development of new magnesium
alloys with high strength and toughness has become a new research hot focus. Previous studies have shown that
the mechanical properties of magnesium alloys can be significantly improved by adding appropriate rare earth
[5–16]. Li et al [17] found that the yield strength, tensile strength and elongation of Mg-Zn alloys with Nd (Mg-
0
.2Zn-3Nd-0.4Zr) are 119 MPa, 186.7 MPa and 10.04% respectively. After aging at 200°C for 16 hours, the yield
strength and tensile strength increased to 140 MPa and 250 MPa, respectively. Chen et al [18] found that the
tensile strength and yield strength of Mg-Zn-Nd alloy with Y (Mg-0.2Zn-6Y-3Nd-0.4Zr) increased to 245 MPa
and 150 MPa respectively, especially the elongation increased to 16%. Wang et al [19] investigated that the
tensile strength and yield strength of both as-cast and aged alloys increase with the increase of Y content. The
maximum tensile strength and yield strength of Mg-Nd-Zn-Zr-1.8% Y alloy could reach 198 MPa and 122 MPa
at room temperature, respectively. The tensile strength could reach 271 MPa and 161 MPa after peak aging
treatment (530 °C/14 h+200°C/12 h). Comparing with Y-free alloys, it increases by 10.6% and 12.6%,
respectively.
The application of magnesium alloys requires not only high strength and toughness, but also good
technological properties, especially casting properties. As a result hot tearing susceptibility (HTS) is important
especially during solidification, which determines the size and structure complexity of parts or billets [20–29]. So
©
2019 IOP Publishing Ltd

Mater. Res. Express 6 (2019) 106535
X Li et al
Table 1. Chemical compositions of experimental
alloys (wt)%.
Alloy
Zn
Y
Nd
Mg
Mg-4.5Zn-6Nd
Mg-4.5Zn-1Y-5Nd
Mg-4.5Zn-3Y-3Nd
Mg-4.5Zn-6Y
4.5
4.5
4.5
4.5
0
1
3
6
6
5
3
0
Bal.
Bal.
Bal.
Bal.
Figure 1. Schematic of experimental setup.
far, about the HTS of Mg-RE-Zn Ternary alloys, Huang et al [30] studied the HTS of alloys (Mg-3Nd-0.2Zn-Zr
alloys) shows that pouring and mold temperatures significant influence on the HTS and the ranges of pouring
and mold temperatures were suggested to be 1003–1033 K and > = 623 K for NZ30K alloy. Liu et al [31] studied
the HTS systematically of Mg-Y-Zn-Zr alloy shows that MgZn(2.5)Y(1)Zr(0.5) alloy has the lowest hot tearing
tendency. However, the HTS of Mg-Y-Nd-Zn alloys with high strength and toughness has not been reported
publicly. In this paper, we tried to systematically analyze the hot tearing tendency of Mg-4.5Zn-xY-yNd
(x+y=6) alloys. In order to exploit new magnesium alloys with high strength, toughness and low HTS
[32–39].
2
. Experimental procedure
2
.1. Experimental materials and processes
The alloy is made of industrial pure magnesium with a purity of 99.95%, industrial pure zinc with a purity of
9.95%, Mg-25% Y and Mg-20% Nd intermediate alloys as raw materials. First, pure magnesium ingots are
9
melted in stainless steel crucible coated with BN on the inner wall. After melting, pure zinc, magnesium-25% Y
and magnesium-20% neodymium master alloys are added in turn. Then, the temperature is adjusted to 700 °C,
holding for 40 min, and poured into the preheated die at 280 C. For the preheat treatment of the mold, the whole
mold is assembled first, then put into the preheater which is adjusted to 280 °C for at least one hour, and take out
when the molten metal is poured. The nominal chemical composition of the refined test alloys is shown in
table 1 [40–43].
Hot tearing experiment is used a T-shaped mold. The schematic is shown in figure 1. It is mainly composed
of a hot tearing casting system, a sensor and a data acquisition system. The solidification temperature data is
collected by a thermocouple inserted into the hot spot. The shrinkage stress acquisition by the sensor through
the connecting rod at the end of the mold, and transmitting to analog-to-digital converter (A/D), then displayed
in the form of data and charts by computer.
2
.2. Double thermocouple analysis system
The solidification curve is collected and analyzed by the double thermocouple analysis system. The schematic
diagram is shown in figure 2. Thermocouples are inserted into the center and edge of the crucible to measure the
center position temperature (T ) and the edge position temperature (T ) during solidification. In order to ensure
c
e
the heat conduction from the radial direction as much as possible, we use thicker asbestos net seal the top of the
crucible. The material used at the bottom is insulating sand and 3 cm thick asbestos to cut heat loss.
2

Mater. Res. Express 6 (2019) 106535
X Li et al
Figure 2. Schematic diagram of double thermocouple test system.
The main purpose of the dual thermocouple analysis system is to determine the dendrite coherence point
[44]. The principle as follows: with the decrease of temperature, the solid phase begins to increase continuously.
Because the thermal conductivity of solid phase and liquid phase is different, the thermal conductivity of solid
phase is larger than that of liquid phase. When dendrites form a continuous network structure, heat diffuses to
the edge more easily through the connected solid phase, which reduces the temperature difference between the
center and the edge. Therefore, the maximum temperature difference between the central thermocouple and the
edge thermocouple indicates that the dendrite begins to coherence. At this time the corresponding temperature
of the central thermocouple is the dendrite coherence temperature (Tcoh).
2
.3. Prediction of alloy HTS by clyne-davies model
The prediction of alloy HTS is based on the assumption of Cyne-Davies model [44]. When the solid fraction ( fs)
between 0.4 and 0.9, the liquid can be flow freely between dendrites, and the solidification shrinkage can be filled
in time. Therefore, the shrinkage stress is fully released without hot tearing, so it is called stress relaxation stage.
When the solid fraction higher than 0.9, the dendrites begin to coherence. The residual liquid phase feeding is
confined and the feeding mechanism also changes from the whole feeding to the local region feeding between the
dendrites. At this time the alloy enters the vulnerable region. As shown in Formula (1), defines the solidification
time of f between 0.4 and 0.9 as t and that of f between 0.9 and 0.99 as t . The ratio of f and f is used as a
s
R
s
v
s
s
parameter CSC (Cracking susceptibility coefficient) for the determination HTS of alloys. The expression as
follows:
tV
t0.99 - t
0.9
CSC =
=
(1)
t
R
t
0.9 - t0.4
t0.99 is the time corresponding to f =0.99; t is the time corresponding to f =0.9; t is the time
s
0.9
s
0.4
corresponding to f =0.4.
s
Since the temperature decreases with time monotonously during solidification, the CSC formula can also be
expressed in another form, as shown in Formula (2). Here, the temperature difference of solid fraction fs
between 0.4 and 0.9 can be expressed by T , between 0.9 and 0.99 can be expressed by T [45, 46].
R
V
TV
T0.99 - T
0.9
CSC* =
=
(2)
T
R
T
0.9 - T0.4
3
. Results and discussion
3
.1. Prediction and characterization of alloys HTS by differential thermal analysis
3
.1.1. HTS Prediction
*
Based on the dual-couple temperature curve and the Clyne-Davies model, the calculated CSC and CSC (Crack
Susceptibility Coefficient) of Mg-4.5Zn-xY-yNd (x+y=6, x=0, 1, 3, 6) alloys are shown in figure 3. The
results show that when the total content of rare earth elements is a constant, the HTS depends on the ratio of Y
*
and Nd [31]. The CSC and CSC of the Mg-4.5Zn-1Y-xNd-0.5Zr alloys are in the following order: Mg-4.5Zn-
3
Y-3Nd>Mg-4.5Zn-1Y-5Nd>Mg-4.5Zn-6Nd>Mg-4.5Zn-6Y.
3
.1.2. Characterization by solidification process
Figure 4 shows the method of double-couple analysis of Mg-4.5Zn-6Y alloy. Under the same cooling conditions,
the lower the dendrite coherence temperature (Tcoh) is, and the larger the solid fraction ( fcoh) is during
coherence, the greater the tendency of hot tearing of alloys.
3

Mater. Res. Express 6 (2019) 106535
X Li et al
Figure 3. HTS of Mg-4.5Zn-xY-yNd alloys: (1). Mg-4.5Zn-6Y; (2). Mg-4.5Zn-3Y-3Nd; (3). Mg-4.5Zn-1Y-5Nd; 4. Mg-4.5Zn-6Nd.
Figure 4. Method of double electric couple analysis of the Mg-4.5Zn-6Y alloy.
Figure 5. Results of double electric couple analysis of Mg-4.5Zn-xY-yNd alloys.
4

Mater. Res. Express 6 (2019) 106535
X Li et al
Figure 6. Shrinkage force and temperature as a function of time for Mg-4.5Zn-xY-yNd alloys: (a) Mg-4.5Zn-3Y-3Nd; (b) Mg-4.5Zn-
1Y-5Nd; (c) Mg-4.5Zn-6Nd; (d) Mg-4.5Zn-6Y.
Figure 5 is the results of double electric couple analysis of Mg-4.5Zn-xY-yNd alloys. It can be seen that the
Tcoh of the Mg-4.5Zn-6Y alloy is the lowest, and the Tcoh of the Mg-4.5Zn-3Y-3Nd alloy is the highest, Which
may be add two rare earth elements at the same time is more likely to be enriched at the front edge of the solid-
liquid interface, and leads to a larger constitutional super-cooling, accelerating dendrite branching and making
α-Mg dendrites coherence prematurely. Tcoh of Mg-4.5Zn-3Y-3Nd, Mg-4.5Zn-1Y-5Nd , Mg-4.5Zn-6Nd and
Mg-4.5Zn-6Y alloys are 618.1 °C, 617.4 °C, 609.0 °C and 595.4 °C, respectively, decreasing order of it consistent
*
with CSC .
3
.2. Characterization by temperature-shrinkage stress curve
Figure 6 shows the curve of solidification shrinkage force (F) versus time (t) and the curve of cooling temperature
T) versus time (t) of Mg-4.5Zn-xY-yNd alloys. Corresponding to figures 6(a)–(d), the solid fractions of initial
cracking are 57.6%, 73.8%, 82.5% and 99.8%, respectively. As shown in table 3, the initial cracking of Mg-
.5Zn-3Y-3Nd, Mg-4.5Zn-1Y-5Nd, Mg-4.5Zn-6Nd occurs before the precipitation of the second phase, that is
(
4
to say, the three alloys correspond to the remaining 42.4%, 26.2% and 17.5% liquid phases respectively. In the
presence of liquid phase between grains, the strength of grain boundaries is proportional to the surface tension
and contact area of liquid phase, and inversely proportional to the thickness of liquid film (Fcrack=2γA/b.
Among them, γ is surface tension of liquid phase, A is contact area between liquid film and matrix, b is the
thickness of liquid film). Obviously, the liquid film thickness of Mg-4.5Zn-3Y-3Nd, Mg-4.5Zn-1Y-5Nd, Mg-
4
.5Zn-6Nd alloys decreases in turn at the initial cracking, which is the main reason for the decrease of their
thermal cracking sensitivity.
In addition, for Mg-4.5Zn-6Y alloy, the initial cracking temperature is lower than that of LPSO phase and
higher than that of W phase. That is to say, the precipitated LPSO phase will play a role in bridging the two sides
of grain boundary to prevent crack growth. Of course, its effect is also related to the nature of LPSO phase itself
and the bonding relationship between LPSO phase and matrix crystals.
3
.3. Characterization by microstructure evolution
Figure 7 shows the as-cast microstructure and precipitated second phase morphology of Mg-4.5Zn-xY-yNd
alloys. Figure 8 shows the XRD diffraction patterns of Mg-4.5Zn-xY-yNd alloys. It can be seen that the main
precipitated phase of the Mg-4.5Zn-6Y alloy is the LPSO phase (Mg ZnY), the main precipitated phase of the
12
Mg-4.5Zn-3Y-3Nd and Mg-4.5Zn-1Y-5Nd alloy is W-phase (Mg Zn (Y,Nd) ),and the main precipitation of
3
3
2
Mg-4.5Zn-6Nd alloy is T-phase (Mg-Zn-Nd ternary phase). Moreover, the morphology of W-phase and
5

Mater. Res. Express 6 (2019) 106535
X Li et al
Figure 7. SEM images of Mg-4.5Zn-xY-yNd alloys: (a) Mg-4.5Zn-6Y; (b) Mg-4.5Zn-3Y-3Nd; (c) Mg-4.5Zn-1Y-5Nd; (d) Mg-4.5Zn-
Nd.
6
Figure 8. XRD spectra of Mg-4.5Zn-xY-yNd alloys: (a) Mg-4.5Zn-3Y-3Nd; (b) Mg-4.5Zn-1Y-5Nd; (c) Mg-4.5Zn-6Y; (d) Mg-4.5Zn-
Nd.
6
T-phase shows a network structure along grain boundaries, while LPSO phase tends to extend from grain
boundary to intragranular direction [47].
The composition of the low melting eutectic phase analyzed by EDS is shown in table 2. LPSO phase is the
main low melting precipitation and a small amount of W-phase (Mg Zn Y ) without adding Nd. With the
3
3 2
change of Y and Nd ratio, LPSO phase disappeared and Mg Zn Y transformed into Mg Zn (Y,Nd) . The main
3
3
2
3
3
2
precipitation is T-phase without Y.
Transmission electron microscope (TEM) patterns of the LPSO phase and W-phase in figures 9(a) and (b),
respectively. The LPSO phase is precipitated by eutectic reaction of residual liquid at 544.7°C, and the atomic
6

Mater. Res. Express 6 (2019) 106535
X Li et al
Table 2. The EDS results of the second phase marked by the white arrows and letters in
figure 4 Mg-4.5Zn-xY-yNd alloys.
Chemical compositions (at%)
Position
Mg
Zn
Y
Nd
Phase
A
B
C
D
E
80.23
69.85
74.91
72.49
64.04
16.81
26.63
21.63
20.28
26.41
2.96
3.52
0.86
1.28
—
—
—
LPSO phase
3 3 2
W-phase(Mg Zn Y )
2.60
5.96
9.55
W-phase Mg
W-phase Mg
3
Zn
Zn
3
3
(Y, Nd)
(Y, Nd)
2
3
2
T-phase
Figure 9. TEM patterns of the Mg-Zn-Y LPSO-phase and W-phase.
stacking is similar to that of a-Mg phase with stacking faults. The distribution of rare earth and zinc atoms is
periodically distributed on stacking faults. Although the lattice constants are different, there is still a certain
coherent relationship between the two phases. Moreover, the strength of the precipitated LPSO phase has a
strong pinning force on both sides of grain boundary of a-Mg.
3
.4. Characterization by Fracture Morphology
Figure 10 shows the fracture morphology of Mg-4.5Zn-xY-yNd alloys. The tearing liquid film of Mg-4.5Zn-3Y-
Nd alloy has thick wrinkles and stretched ‘Wiredrawing’ on the fracture surface in figure 10(a). According to
3
the and F-t curves of Mg-4.5Zn-3Y-3Nd, the first hot tearing initiation at the temperature of 539.9°C and solid
fraction is 57.6%, Because there are still more liquid phase remaining at this time, the crack is fully fed. However,
the solidification shrinkage stress increases further during solidification, and the second crack forms at the
temperature of 499.5°C ( f =92.6%), the feeding position is stretched again. indicating that Mg-4.5Zn-3Y-3Nd
s
alloy has high HTS. Figures 10(b), (c) shows that the folded liquid film obvious decrease compared with
figure 10(a), indicating that the liquid fraction is low and the crack initiation is late relatively. The low melting
phase can fed the crack and reduce the tendency of hot tearing to some extent. This is consistent with the analysis
of the temperature-stress curve, so these two alloys have low HTS than the alloy of figure 10(a). By observing the
thickness and continuity of the tear film, As shown in figure 10(d), it is caused by minute cracks initiation at the
end of the solidification. At this time, the strength of the alloy is close to the maximum, and the crack is difficult
to propagation, so the hot tearing resistance is the best.
3
.5. Characterization by thermal analysis curve
Figure 11 shows the cooling curve, first derivative curve and baseline determined by Newton baseline method of
Mg-4.5Zn-xY-yNd alloys. When there is inflection point in the cooling curve and exothermic peak in the first
derivative curve of temperature, it indicates that the latent heat of crystallization is released and a new phase is
precipitated in the liquid phase. The temperatures of each precipitation in the figure 11 are shown in table 3.
It can be seen from figure 11 and table 3 that the latent heat peak and precipitation temperature of the second
phase of Mg-4.5Zn-3Y-3Nd alloy, Mg-4.5Zn-1Y-5Nd alloy, Mg-4.5Zn-6Nd alloy and Mg-4.5Zn-6Y alloy
increase in turn, which indicates that the residual liquid phase between the dendrites increases sequentially after
the precipitation of the α-Mg phase. As a result, not only the feeding capacity of the residual liquid phase
7

Mater. Res. Express 6 (2019) 106535
X Li et al
Figure 10. Fracture morphologies of Mg-4.5Zn-xY-yNd alloys: (a) Mg-4.5Zn-3Y-3Nd; (b) Mg-4.5Zn-1Y-5Nd; (c) Mg-4.5Zn-6Nd;
d) Mg-4.5Zn-6Y.
(
Figure 11. Solidification path of Mg-4.5Zn-xY-yNd alloys: (a) Mg-4.5Zn-3Y-3Nd; (b) Mg-4.5Zn-1Y-5Nd (c); Mg-4.5Zn-6Nd; (d)
Mg-4.5Zn-6Y.
8

Mater. Res. Express 6 (2019) 106535
X Li et al
Table 3. Thermal analysis results for the characteristic temperatures for Mg-4.5Zn-xY-yNd alloys.
Alloy
α-Mg
LPSO phase
W-phase
T-phase
T
S
Mg-4.5Zn-3Y-3Nd
Mg-4.5Zn-1Y-5Nd
Mg-4.5Zn-6Nd
Mg-4.5Zn-6Y
626.8 °C
628.3 °C
628.8 °C
631.9 °C
—
—
496.4 °C
504.7 °C
—
—
—
469.2 °C
485.0 °C
490.8 °C
504.8 °C
—
505.8 °C
—
544.7 °C
525.4° C
Figure 12. Comparison between HTI predicted and the distribution of stress using ProCAST of Mg-4.5Zn-xY-yNd alloys at mold
temperature of 280°C: (a) Mg-4.5Zn-6Y; (b) Mg-4.5Zn-6Nd; (c) Mg-4.5Zn-1Y-5Nd; (d) Mg-4.5Zn-3Y-3Nd.
between the dendrites is improved, but also the local temperature rise between the dendrites is increased to
relieve the solidification shrinkage stress and reduce the HTS of the alloy.
3
.6. Numerical simulation of HTS
Figure 12 shows the calculated Hot Tearing Indicator (HTI) and Stress at the hot spot for Mg-4.5Zn-xY-yNd
alloys. HTI provide a good indication for the susceptibility of the hot tearing occurred during solidification. The
simulation results show that the hot tearing tendency of Mg-4.5Zn-6Y alloy, as shown in figure 12(a), is
obviously different from that of the other three alloys. Its HTI value is the smallest and stress distribution at the
hot spot is more uniform. When the ratio of Nd is 3%, the HTS is the highest. The susceptibility of hot tearing
predicted by numerical simulation is in good agreement with that obtained by experimental observations.
4
. Conclusion
(
1) When the total content of (Y+Nd) in the alloy is constant (6 wt%), the predicted and measured HTS of
Mg-4.5Zn-xY-yNd alloys changes with the relative content of Y and Nd. The order from high to low is Mg-
4.5Zn-3Y-3Nd, Mg-4.5Zn-1Y-5Nd, Mg-4.5Zn-6Nd, Mg-4.5Zn-6Nd and Mg-4.5Zn-6Y.
(
2) The precipitations have an important effect on the hot tearing tendency of Mg-4.5Zn-xY-yNd alloys. The
latent heat peak and precipitation temperature of the second phase of Mg-4.5Zn-3Y-3Nd alloy, Mg-4.5Zn-
1Y-5Nd alloy, Mg-4.5Zn-6Nd alloy and Mg-4.5Zn-6Y alloy increase sequentially, which not only improves
9

Mater. Res. Express 6 (2019) 106535
X Li et al
the feeding capacity of the residual liquid phase between dendrites, but also increases the local temperature
between dendrites to alleviate the solidification shrinkage stress and reduce the HTS of the alloys.
(
3) According to the fracture temperature and solid fraction of the alloys, hot tearing occurs in the middle and
late solidification stages, and the interdendritic liquid phase and its crystallization behavior have a great
influence on the hot tearing. The residual liquid phase with eutectic composition feeding and the coherent
extension of the second phase precipitated at high temperature to the matrix can effectively pin grain
boundaries and inhibit the nucleation and growth of hot cracks.
Acknowledgments
This work is supported by the National Natural Science Foundation of China (Grant No.51571145) and Ningbo
Science and Technology Innovation 2025 Major Project (Project name: Research on precision forming
technology of new energy automobile lightweight magnesium alloy material).
Disclosure statement
No potential conflict of interest is reported by the authors.
ORCID iDs
Xingxing Li https: // orcid.org/0000-0001-8470-5371
Yue Wang https: // orcid.org/0000-0002-7272-7589
Ziqi Wei https: // orcid.org/0000-0002-9883-0269
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