**2.3. Microstructure characterization**

4 Recent Developments in the Study of Recrystallization

AM31 alloys was 20 mm. The discussion pertaining to the recrystallization behaviors was based on the warm-rolling and annealing processes of the AM31 and AZ31B samples.

H90 H45 H0

**Figure 2.** Uniaxial samples taken from the ZK60 billet along various directions with regard to the rolling direction (RD) and normal direction (ND). V0, V45 and V90 represent the samples taken from the RD to the ND, while H0, H45 and H90 represent

Uniaxial compression tests were carried out using the Thermecmastor-Z (Fuji Electronic Industrial Co.). Cylindrical AZ31B billets with a diameter of 9 mm and a length of 12 mm were used for the compression tests. The other alloys, ZK60 alloys, were machined into

The deformation temperatures of the AZ31B billets were 473 K (200 ◦C), 523 K (250 ◦C), and 573 K (300 ◦C), while the strain rates were 0.00139/s and 0.139/s. Ex-situ experiments to determine the microstructural evolution were also carried out at a temperature of 523 K (250 ◦C) and a strain rate of 0.32/s. For the ex-situ compression, the sample was marked with micro-indentations and compression and EBSD measurements were then alternately

Uniaxial compression tests for the ZK60 alloys were also carried out at various temperatures and strain rates. Wider deformation temperatures were imposed on the ZK60 alloys than on the AZ31B samples, and the temperatures were 298 K (25 ◦C), 398 K (125 ◦C), 448 K (175 ◦C), 498 K (225 ◦C), 548 K (275 ◦C), 598 K (325 ◦C), and 698 K (425 ◦C). Two different strain rates were used, 0.0069/s and 0.139/s. At total strain values of 3% and 7% at a strain rate of 0.139/s, microstructural mapping was carried out using EBSD. Each cylindrical sample was prepared according to the specimen preparation sequence for EBSD mapping before compression, after which the uniaxial compression and EBSD mapping were repeated

Figure 3 shows a schematic diagram of the cylindrical sample and the EBSD measurement region. The extrusion direction is parallel to the compression direction. The orientation color

compression samples 12 mm in length and 8 mm in diameter, as shown in Fig. 2.

alternately to determine the microstructural evolution during compression.

code of the EBSD inverse pole figure maps is also shown.

V90 V45 V0

the samples taken from the RD to the transverse direction (TD).

**2.2. Thermo-mechanical processing**

repeated.

RD TD ND

> Characterization of the microstructure and texture was mainly carried out using EBSD (electron backscatter diffraction). An automated HR-EBSD (JEOL7001F) with a HKL Channel-5 and the generalized EBSD data analysis code REDS [23] were both used. EBSD samples were mechanically polished and then electropolished using a solution of butyl cellosolve (50 ml), ethanol (10 ml) and perchloric acid (5 ml) at a voltage of 10 V and at temperatures ranging from 253 K (−20 ◦C) to 258 K (−15 ◦C).
