**3. Deformation of Mg alloys**

Textural and microstructural evolution and associated mechanical responses were investigated during the uniaxial compression of the Mg alloys at various temperatures and strain rates. Two different Mg alloys of extruded AZ31B billets and ingot-casted ZK60 alloys were prepared for the mechanical tests.

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**Figure 5.** Flow curve with the ex-situ EBSD mapping points of extruded AZ31B billets

lines and the GID of 2 ◦ is denoted by the thin lines.

amount of low angle frequency develops.

deformation.

The extruded AZ31B billets contained typical extrusion textures. The texture and microstructure quickly changed upon deformation. Twinning activity was evident during compression. Approximately, a strain of 3% caused most of the blue and green grains to contain tensile twinning, which denotes a {1012¯ }�1010¯ � or 86◦�1210 ¯ � misorientation relationship. At a strain of 5%, twinning grew very fast. Nearly the entire region underwent twinning at a strain of 8%. As the deformation degree increased, the EBSD inverse pole figure contained more of a non-indexed region, as shown in black. Grain boundary maps are also presented in Fig. 7. A grain identification (GID) angle of 15 ◦ is denoted by the thick

Reorientation of the grains during uniaxial compression can also be found easily using pole figures (PFs), as shown in Fig 8. The coordinates of X0 and Y0 correspond to the extrusion (ED) or compression (CD), and the transverse (TD) directions, respectively. As-extruded billets have a fiber texture along the TD, which is typical in the texturing of extruded samples. This stems from the grain reorientation during uniaxial compression, in which the basal planes are parallel to the billet surface. With an increase of the deformation, many tensile twins occurred and grew into parent regions. Strong intensity near the X0 or ED direction reflects the twinning. The maximum intensity in the pole figures also increases with the

Misorientation angle distributions are shown in Fig. 9. The solid line represents the misorientation angle distribution of randomly orientated hexagonal polycrystals. The as-received billets show a distribution similar to that of a random distribution. At a strain of 1%, a strong peak arises around a misorientation angle of 86◦, which is associated with tensile twinning. This was most frequently observed at a strain of 3%, after which the frequency of low misorientation angles of less than 15◦ gradually increases. At a strain of 13%, a great

**Figure 4.** Uniaxial compression of extruded AZ31B billets at various temperatures and deformation rates

## **3.1. Extruded AZ31B billets**

Figure 4 shows the flow curves of the extruded AZ31B billets during uniaxial compression. All three temperatures of 473 K (200 ◦*C*), 523 K (250 ◦*C*), and 573 K (300 ◦*C*) show the peak strength values, after which they decrease with the strain. With an increase in the compression temperature from 473 K (200 ◦*C*) to 573 K (300 ◦*C*), the peak strength also gradually decreases. The peak value in the strength implies some dynamic process during compression at that temperature and strain rate. The highest peak strength is found at a strain rate of 0.14/s and a temperature of 473 K (200 ◦*C*). Even at the same temperature, the lower deformation rate of 0.0014/s results in a low value of the peak strength. When considering the elongation during compression at 473 K (200 ◦*C*), the high deformation rate of 0.14/s results in a rapid failure at around 35%. In contrast, the low deformation rate of 0.0014/s reveals a more active dynamic process and the elongation continues, reaching more than 60% past the peak strength. As expected, the lowest strength is observed at a strain rate of 0.0014/s and a temperature of 573 K (300 ◦*C*). Overall, high temperature conditions of 523 K (250 ◦*C*) and 573 K (300 ◦*C*) enhance the elongation until it is greater than 60%.

Ex-situ EBSD measurements of the extruded AZ31B billets during uniaxial compression were carried out on the side, with the samples polished until they had a flat surface, as shown in Fig. 3. Figure 5 shows the flow curve with the ex-situ EBSD measuring points of the extruded AZ31B billets shown in Fig. 5. Open circles illustrate the various strains corresponding to the EBSD measurements. The EBSD measurements were taken of the sample before the peak strength.

Figure 6 presents the textural and microstructural evolution during the uniaxial compression of the extruded AZ31B billets. Micro-indentations were used to identify the mapping area during deformation. The initial microstructure reveals some mixture of large and small grains from the inverse pole figure (IPF) map shown in Fig. 6(a). The IPF maps were plotted based on the extrusion direction (ED), and thus both blue and green on the IPF imply that the �21¯10¯ � and the �1010¯ � directions align to the ED, respectively. Note the Fig. 3(b).

**Figure 5.** Flow curve with the ex-situ EBSD mapping points of extruded AZ31B billets

6 Recent Developments in the Study of Recrystallization

**3.1. Extruded AZ31B billets**

strength.

**Figure 4.** Uniaxial compression of extruded AZ31B billets at various temperatures and deformation rates

K (250 ◦*C*) and 573 K (300 ◦*C*) enhance the elongation until it is greater than 60%.

Ex-situ EBSD measurements of the extruded AZ31B billets during uniaxial compression were carried out on the side, with the samples polished until they had a flat surface, as shown in Fig. 3. Figure 5 shows the flow curve with the ex-situ EBSD measuring points of the extruded AZ31B billets shown in Fig. 5. Open circles illustrate the various strains corresponding to the EBSD measurements. The EBSD measurements were taken of the sample before the peak

Figure 6 presents the textural and microstructural evolution during the uniaxial compression of the extruded AZ31B billets. Micro-indentations were used to identify the mapping area during deformation. The initial microstructure reveals some mixture of large and small grains from the inverse pole figure (IPF) map shown in Fig. 6(a). The IPF maps were plotted based on the extrusion direction (ED), and thus both blue and green on the IPF imply that

the �21¯10¯ � and the �1010¯ � directions align to the ED, respectively. Note the Fig. 3(b).

Figure 4 shows the flow curves of the extruded AZ31B billets during uniaxial compression. All three temperatures of 473 K (200 ◦*C*), 523 K (250 ◦*C*), and 573 K (300 ◦*C*) show the peak strength values, after which they decrease with the strain. With an increase in the compression temperature from 473 K (200 ◦*C*) to 573 K (300 ◦*C*), the peak strength also gradually decreases. The peak value in the strength implies some dynamic process during compression at that temperature and strain rate. The highest peak strength is found at a strain rate of 0.14/s and a temperature of 473 K (200 ◦*C*). Even at the same temperature, the lower deformation rate of 0.0014/s results in a low value of the peak strength. When considering the elongation during compression at 473 K (200 ◦*C*), the high deformation rate of 0.14/s results in a rapid failure at around 35%. In contrast, the low deformation rate of 0.0014/s reveals a more active dynamic process and the elongation continues, reaching more than 60% past the peak strength. As expected, the lowest strength is observed at a strain rate of 0.0014/s and a temperature of 573 K (300 ◦*C*). Overall, high temperature conditions of 523

The extruded AZ31B billets contained typical extrusion textures. The texture and microstructure quickly changed upon deformation. Twinning activity was evident during compression. Approximately, a strain of 3% caused most of the blue and green grains to contain tensile twinning, which denotes a {1012¯ }�1010¯ � or 86◦�1210 ¯ � misorientation relationship. At a strain of 5%, twinning grew very fast. Nearly the entire region underwent twinning at a strain of 8%. As the deformation degree increased, the EBSD inverse pole figure contained more of a non-indexed region, as shown in black. Grain boundary maps are also presented in Fig. 7. A grain identification (GID) angle of 15 ◦ is denoted by the thick lines and the GID of 2 ◦ is denoted by the thin lines.

Reorientation of the grains during uniaxial compression can also be found easily using pole figures (PFs), as shown in Fig 8. The coordinates of X0 and Y0 correspond to the extrusion (ED) or compression (CD), and the transverse (TD) directions, respectively. As-extruded billets have a fiber texture along the TD, which is typical in the texturing of extruded samples. This stems from the grain reorientation during uniaxial compression, in which the basal planes are parallel to the billet surface. With an increase of the deformation, many tensile twins occurred and grew into parent regions. Strong intensity near the X0 or ED direction reflects the twinning. The maximum intensity in the pole figures also increases with the deformation.

Misorientation angle distributions are shown in Fig. 9. The solid line represents the misorientation angle distribution of randomly orientated hexagonal polycrystals. The as-received billets show a distribution similar to that of a random distribution. At a strain of 1%, a strong peak arises around a misorientation angle of 86◦, which is associated with tensile twinning. This was most frequently observed at a strain of 3%, after which the frequency of low misorientation angles of less than 15◦ gradually increases. At a strain of 13%, a great amount of low angle frequency develops.

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(a) (b)

(c) (d)

(e) (f)

**Figure 8.** Pole figures obtained from EBSD mapping (AZ31B billets). The coordinates of X0 and Y0 correspond to the extrusion (ED) or compression (CD), and the transverse (TD) directions, respectively. (a) as-extruded, (b) 1%, (c) 3%, (d) 5%, (e) 8%, and

**Figure 9.** Misorientation distribution obtained from EBSD mapping (AZ31B billets).

(f) 13%

**Figure 6.** Inverse pole figure maps (IPFs) obtained along the extrusion direction (ED) or compression direction (CD) of the AZ31B billets. The grain identification angle (GID) is 15 ◦. The step size for the EBSD measurements is 2 µm for as-extruded sample and 1 µm for others, and the scale bar at the bottom of the IPF maps is 200 µm. (a) as-extruded, (b) 1%, (c) 3%, (d) 5%, (e) 8%, and (f) 13%

**Figure 7.** Grain boundary maps obtained from EBSD mapping (AZ31B billets). The grain identification angle (GID) is 15 ◦. The step size for the EBSD measurements is 2 µm for as-extruded sample and for others 1 µm and the scale bar at the bottom of the IPF maps is 200 µm. (a) as-extruded, (b) 1%, (c) 3%, (d) 5%, (e) 8%, and (f) 13%

8 Recent Developments in the Study of Recrystallization

5%, (e) 8%, and (f) 13%

(a) (b) (c)

(d) (e) (f)

**Figure 6.** Inverse pole figure maps (IPFs) obtained along the extrusion direction (ED) or compression direction (CD) of the AZ31B billets. The grain identification angle (GID) is 15 ◦. The step size for the EBSD measurements is 2 µm for as-extruded sample and 1 µm for others, and the scale bar at the bottom of the IPF maps is 200 µm. (a) as-extruded, (b) 1%, (c) 3%, (d)

(a) (b) (c)

(d) (e) (f)

**Figure 7.** Grain boundary maps obtained from EBSD mapping (AZ31B billets). The grain identification angle (GID) is 15 ◦. The step size for the EBSD measurements is 2 µm for as-extruded sample and for others 1 µm and the scale bar at the bottom of

the IPF maps is 200 µm. (a) as-extruded, (b) 1%, (c) 3%, (d) 5%, (e) 8%, and (f) 13%

**Figure 8.** Pole figures obtained from EBSD mapping (AZ31B billets). The coordinates of X0 and Y0 correspond to the extrusion (ED) or compression (CD), and the transverse (TD) directions, respectively. (a) as-extruded, (b) 1%, (c) 3%, (d) 5%, (e) 8%, and (f) 13%

**Figure 9.** Misorientation distribution obtained from EBSD mapping (AZ31B billets).

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(a) (b)

(c) (d)

(e)

**Figure 11.** Pole figures of ZK60 alloys obtained from EBSD mapping (*ε* = 3%, *ε*˙ = 0.139/s). The coordinates of X0 and Z0 correspond to the RD and extrusion direction (ED), respectively. (a) 448 K (175 ◦C), (b) 498 K (225 ◦C), (c) 548 K (275 ◦C), (d)

The variation of the basal intensity is more evident in Fig. 11, which shows pole figures computed from the EBSD mapping in Fig. 10. The initial sample showed weak basal intensity along the X0 or the normal direction (ND) of the initial billet, as shown in Fig. 2. During compression, the grains were reoriented into the center of the pole figures, Z0, or in the extrusion direction (ED). With an increase in the temperature, the overall basal intensity decreased. At a temperature of 698 K (425 ◦), the twinned region is small and the basal intensity in the center is comparatively low. It was noted that a high temperature affects twinning activation and propagation during compression, as less twinning was observed, as shown in Fig. 11(e). Note that the intensity in the center of the pole figure only appears slight in Fig. 11(e). Strong twinning activity results in a sharp increase in the basal intensity, which appears in the center of the (0002) pole figure. The maximum intensity found in Fig. 11(e) is associated with the initial large grains in Fig. 10(e), not with textural evolution due to compression. In fact, a texture analysis using EBSD mapping contains some statistical uncertainty coming from spatial limitations, and statistical uncertainty should therefore be assumed, unlike in the XRD texture analysis, which usually covers a large area and numerous

The grain structure at a strain of 7% resulted in finer grains, as shown in Fig. 12, than that at a strain of 3 %, as shown in Fig. 10. Strong twinning activation and basal slip up to 598 K (325 ◦C) seem to increase the basal intensity further; thus, most grains appear in red, a result that is related to the basal fiber. In fact, more complicated activation of various deformation modes shown in Table 1 occurs during compression. Note that at a temperature of 698 K

598 K (325 ◦C), and (e) 698 K (425 ◦C)

grains.

(e)

**Figure 10.** Inverse pole figure (IPF) maps obtained along the extrusion direction (ED) or compression direction (CD) of the ZK60 alloys (*ε* = 3%, *ε*˙ = 0.139/s). The grain identification angle (GID) is 15 ◦. The step size for the EBSD measurements is 1 µm, and the scale bar at the bottom of the IPF maps is 200 µm. (a) 448 K (175 ◦C), (b) 498 K (225 ◦C), (c) 548 K (275 ◦C), (d) 598 K (325 ◦C), and (e) 698 K (425 ◦C)

#### **3.2. Ingot-casted ZK60 billets**

The initial microstructure of the ingot-casted ZK60 alloys possessed an equi-axed grain structure with a weak basal texture.

During the uniaxial compression of the ZK60 alloys, the microstructural and textural evolution was investigated with the temperature. Figure 10 shows inverse pole figure maps of ZK60 at a strain and strain rate of 3% and 0.139/s, respectively. Tensile twinning boundaries are specified in red.

10 Recent Developments in the Study of Recrystallization

(325 ◦C), and (e) 698 K (425 ◦C)

are specified in red.

**3.2. Ingot-casted ZK60 billets**

structure with a weak basal texture.

(a) (b)

(c) (d)

(e)

**Figure 10.** Inverse pole figure (IPF) maps obtained along the extrusion direction (ED) or compression direction (CD) of the ZK60 alloys (*ε* = 3%, *ε*˙ = 0.139/s). The grain identification angle (GID) is 15 ◦. The step size for the EBSD measurements is 1 µm, and the scale bar at the bottom of the IPF maps is 200 µm. (a) 448 K (175 ◦C), (b) 498 K (225 ◦C), (c) 548 K (275 ◦C), (d) 598 K

The initial microstructure of the ingot-casted ZK60 alloys possessed an equi-axed grain

During the uniaxial compression of the ZK60 alloys, the microstructural and textural evolution was investigated with the temperature. Figure 10 shows inverse pole figure maps of ZK60 at a strain and strain rate of 3% and 0.139/s, respectively. Tensile twinning boundaries

**Figure 11.** Pole figures of ZK60 alloys obtained from EBSD mapping (*ε* = 3%, *ε*˙ = 0.139/s). The coordinates of X0 and Z0 correspond to the RD and extrusion direction (ED), respectively. (a) 448 K (175 ◦C), (b) 498 K (225 ◦C), (c) 548 K (275 ◦C), (d) 598 K (325 ◦C), and (e) 698 K (425 ◦C)

The variation of the basal intensity is more evident in Fig. 11, which shows pole figures computed from the EBSD mapping in Fig. 10. The initial sample showed weak basal intensity along the X0 or the normal direction (ND) of the initial billet, as shown in Fig. 2. During compression, the grains were reoriented into the center of the pole figures, Z0, or in the extrusion direction (ED). With an increase in the temperature, the overall basal intensity decreased. At a temperature of 698 K (425 ◦), the twinned region is small and the basal intensity in the center is comparatively low. It was noted that a high temperature affects twinning activation and propagation during compression, as less twinning was observed, as shown in Fig. 11(e). Note that the intensity in the center of the pole figure only appears slight in Fig. 11(e). Strong twinning activity results in a sharp increase in the basal intensity, which appears in the center of the (0002) pole figure. The maximum intensity found in Fig. 11(e) is associated with the initial large grains in Fig. 10(e), not with textural evolution due to compression. In fact, a texture analysis using EBSD mapping contains some statistical uncertainty coming from spatial limitations, and statistical uncertainty should therefore be assumed, unlike in the XRD texture analysis, which usually covers a large area and numerous grains.

The grain structure at a strain of 7% resulted in finer grains, as shown in Fig. 12, than that at a strain of 3 %, as shown in Fig. 10. Strong twinning activation and basal slip up to 598 K (325 ◦C) seem to increase the basal intensity further; thus, most grains appear in red, a result that is related to the basal fiber. In fact, more complicated activation of various deformation modes shown in Table 1 occurs during compression. Note that at a temperature of 698 K

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(a) (b)

(c) (d)

(e)

**Figure 13.** Pole figures of ZK60 alloys obtained from EBSD mapping (*ε* = 7%, *ε*˙ = 0.139/s). The coordinates of X0 and Z0 correspond to the RD and extrusion direction (ED), respectively. (a) 448 K (175 ◦C), (b) 498 K (225 ◦C), (c) 548 K (275 ◦C), (d)

(a) (b)

**Figure 14.** Misorientation distributions obtained from the EBSD mapping of ZK60. (a) *ε* = 3% (Fig. 10) and (b) *ε* = 7% (Fig. 12)

598 K (325 ◦C), and (e) 698 K (425 ◦C)

**Figure 12.** Inverse pole figure (IPF) maps obtained along the extrusion direction (ED) or compression direction (CD) of the ZK60 alloys (*ε* = 7%, *ε*˙ = 0.139/s). The grain identification angle (GID) is 15 ◦. The step size for the EBSD measurements is 1 µm, and the scale bar at the bottom of the IPF maps is 200 µm. (a) 448 K (175 ◦C), (b) 498 K (225 ◦C), (c) 548 K (275 ◦C), (d) 598 K (325 ◦C), and (e) 698 K (425 ◦C)

(425 ◦*C*), twinning activation is also weakest among other temperature conditions, as shown in at a strain of 3% in Fig. 11(e). Pole figures for the EBSD mapping data in Fig. 12 are shown in Fig. 13. Compared to the PFs at a low strain of 3% in Fig. 11, basal intensity in the center of the pole figures is much more evident in Fig. 13. It was also found that some variation arises in the maximum intensity as the temperature changes. The greatest maximum intensity among the PFs is observed in Fig. 13(c), and this appears to be related to the initially large grains, as discussed in Fig. 11(e).

The misorientation angle distributions at strains of 3% and 7% are given in Fig. 14. A very typical angle distribution is found. The most dominant frequency is observed near tensile twinning. At a large strain of 7%, a higher frequency occurs with misorientation angles smaller than 15 ◦. This is related to the subgrain boundaries due to increase in plastic strain.

12 Recent Developments in the Study of Recrystallization

(325 ◦C), and (e) 698 K (425 ◦C)

grains, as discussed in Fig. 11(e).

(a) (b)

(c) (d)

(e)

**Figure 12.** Inverse pole figure (IPF) maps obtained along the extrusion direction (ED) or compression direction (CD) of the ZK60 alloys (*ε* = 7%, *ε*˙ = 0.139/s). The grain identification angle (GID) is 15 ◦. The step size for the EBSD measurements is 1 µm, and the scale bar at the bottom of the IPF maps is 200 µm. (a) 448 K (175 ◦C), (b) 498 K (225 ◦C), (c) 548 K (275 ◦C), (d) 598 K

(425 ◦*C*), twinning activation is also weakest among other temperature conditions, as shown in at a strain of 3% in Fig. 11(e). Pole figures for the EBSD mapping data in Fig. 12 are shown in Fig. 13. Compared to the PFs at a low strain of 3% in Fig. 11, basal intensity in the center of the pole figures is much more evident in Fig. 13. It was also found that some variation arises in the maximum intensity as the temperature changes. The greatest maximum intensity among the PFs is observed in Fig. 13(c), and this appears to be related to the initially large

The misorientation angle distributions at strains of 3% and 7% are given in Fig. 14. A very typical angle distribution is found. The most dominant frequency is observed near tensile twinning. At a large strain of 7%, a higher frequency occurs with misorientation angles smaller than 15 ◦. This is related to the subgrain boundaries due to increase in plastic strain.

**Figure 13.** Pole figures of ZK60 alloys obtained from EBSD mapping (*ε* = 7%, *ε*˙ = 0.139/s). The coordinates of X0 and Z0 correspond to the RD and extrusion direction (ED), respectively. (a) 448 K (175 ◦C), (b) 498 K (225 ◦C), (c) 548 K (275 ◦C), (d) 598 K (325 ◦C), and (e) 698 K (425 ◦C)

**Figure 14.** Misorientation distributions obtained from the EBSD mapping of ZK60. (a) *ε* = 3% (Fig. 10) and (b) *ε* = 7% (Fig. 12)

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H90\_498K

Deformation and Recrystallization Behaviors in Magnesium Alloys

H45\_498K H0\_498K

H45\_498K H0\_498K H90\_498K

The recrystallization behavior of magnesium alloys was investigated during warm rolling and the subsequent annealing processes. Usually, plastic works of magnesium alloys, including rolling, extrusion, and forming processes, are performed at elevated temperatures. In the previous section, uniaxial compression carried out at various elevated temperatures was discussed. During the warm processing of the samples, dynamic recrystallization can occur depending on the temperature and the total strain. The as-rolled sheets are usually annealed before the next forming process; thus, the texture and microstructure are expected to change. In this section, two different cases of recrystallization - dynamic recrystallization and static recrystallization - are presented. Static recrystallization at the shear band region is

Large and small grains are mixed as shown in Fig. 17. Particularly, small grains are located between the large grains, which show similar orientations based on the orientation colors and pole figures. It was noted that a shear band forms inside large grains during hot deformation. The small grains are dynamically-recrystallized. Inside the large grains, numerous low-angle grain boundaries with thin black lines and tensile twins, as specified by the red grain

The warm-rolled sheets show a mixture of large and small grains, as shown in Fig. 18. It appears that the initial large grains are shattered into various sizes of grains during the warm rolling process. During static annealing for 10 min at 573 K (300 ◦C), the as-rolled structure becomes a fully-recrystallized grain structure, with all grain shapes equi-axed. There exists some variation in the grain sizes of the annealed sheets. The overall textures of both the as-rolled and annealed sheets revealed similar basal fibers. The basal intensity of the as-roll

**Figure 16.** Flow curves obtained from ZK60 alloys along the horizontal direction (see Fig. 2).

**4.1. Dynamic recrystallization of hot-rolled AM31 alloys**

**4.2. Static recrystallization of warm-rolled AZ31B alloys**

**4. Recrystallization of Mg alloys**

also discussed.

boundaries, are also observed.

**Figure 15.** Flow curves obtained from ZK60 alloys. (a) V0, (b) V45, and (c) V90 at a deformation rate of 0.139/s. (d) V0, (e) V45, and (f) V90 at a deformation rate of 0.0069/s.

The flow curves obtained during the uniaxial compression of the ZK60 alloys along the vertical direction are shown in Fig. 15. There are some differences between a high strain rate (0.139/s) and a low strain rate (0.0069/s). For a low strain rate of 0.0069/s, low temperatures of 298 K (25 ◦C) and 398 K (125 ◦C) were additionally assessed. The low temperatures cannot provide enough deformation modes, and the elongation at the temperatures is less than it is at other temperatures. The high strain rate of 0.139 imparts higher strength than that at the low strain rate of 0.0069. At a temperature of 448 K (175 ◦C), it is clear that a strain of 0.0069 shows more extended elongation than a strain of 0.139. The flow curves in Fig. 15(a) correspond to the microstructures examined above in Figs. 10 and 12. The samples taken from the different direction respond differently to external loading or compression. The samples referred to as V0 show the most dominant twinning; thus, some stress relaxation occurs during hardening (Figs. 15(a) and 15(d)). The samples termed V45 revealed some linear strain-hardening behavior (Figs. 15(b) and 15(e)). The samples referred to as V90 demonstrated typical non-linear strain-hardening behavior of the type usually found during the plastic deformation of polycrystalline materials (Figs. 15(c) and 15(f)). Note the curvature of the non-linear strain-hardening regions in the flow curves between V0 and V90. The former shows negative curvature, while the latter shows positive curvature.

Other flow curves obtained along the horizontal direction are shown in Fig. 16. At a high temperature of 498 K, the elongation is better than it is at a low temperature of 448 K. The strain-hardening behaviors of all samples measured from the horizontal directions, H0, H45, and H90, are similar to those of V0, as shown in Fig. 15(a). All show negative curvature during strain hardening, which implies that strong twinning occurred during warm compression.

**Figure 16.** Flow curves obtained from ZK60 alloys along the horizontal direction (see Fig. 2).
