The Effect of Ti Particles Addition on the Microstructure and Mechanical Behavior of Mg AZ31/Al 6082 Composite Sheets

In this study, Ti particles reinforced Mg AZ31/Al 6082 composite sheets were successfully prepared by hot rolling, with the aim of revealing the effect of Ti particles addition on the mechanical behavior and microstructure of Mg AZ31/Al 6082 composite sheets. The results showed that Ti particles were uniformly distributed at the interface of the Mg/Al-Ti composite sheets, which could greatly reduce the amount of Mg-Al intermetallic compounds during annealing treatment. Compared to the Mg/Al sheet, the tensile strength and elongation of the Mg/Al-Ti sheet could be improved simultaneously after the annealing treatment. Ti particles addition hardly affected the grain size, texture type, and tensile fracture morphology of the Mg layer and Al layer in the composite sheets before and after annealing. This present study provides a new perspective on the mechanical behavior and microstructure of Mg/Al composites through the addition of metal particles.

Various Mg/Al composite sheets have been successfully prepared by rolling bonding [23][24][25], friction stir welding [26,27], explosive welding [28,29], co-extrusion [11,15,30], and diffusion bonding [31,32], etc. For example, explosive welding is more beneficial to join the two metals whose properties differ greatly, but there is some danger in its experimental process [28,29]. Co-extrusion can improve the formability of a composite sheet, but its preparation process is complicated [11,15,30]. Among these techniques, rolling bonding is the most effective method for industrial applications because of its low production cost, good quality, and easy implementation of mass production. Previous publications have reported that Mg-Al intermetallic compounds (IMCs) were generated easily at the interface of the Mg/Al composites during the hot process and subsequent annealing treatment [15,18]. However, these brittle IMCs can greatly affect the mechanical properties of the composites. In our recent publications, the results showed that a very thick diffusion layer (about 300 µm), constituted of abundant Mg-Al IMCs, greatly weakened the mechanical The materials that were used in the present study were commercial Ti particles, Al 6082 sheet, and Mg AZ31 sheet. The high-purity spherical Ti particles (TA0, Grade 1), with an average size of 100 µm, were supplied by Nantong Jinyuan intelligent company, China. The Al 6082 sheet (thickness of 1 mm) and Mg AZ31 sheet (thickness of 4 mm) were supplied by Shenzhen Shunjinda company, China. The Mg and Al sheets were cut into widths of 125 mm and lengths of 250 mm. The surfaces of the raw sheets were polished with a steel brush. As seen in Figure 1, the Mg and Al sheets were stacked by sequence of 6082/AZ31/6082, and 20 g of the Ti particles were spread evenly between the AZ31 sheet and 6082 sheet. The stacked sheet was placed in an air furnace at 400 • C for 0.25 h and subsequently rolled by a single pass, using a rolling speed of 2 m/min. In order to effectively inhibit the oxidation of the Ti particles, sulfur powder was placed in a muffle furnace to consume the oxygen in the furnace. The final rolled composite sheet (the designated Mg/Al-Ti) had a thickness of 2.7 mm along the normal direction (ND). For comparison, a Mg/Al composite sheet without Ti particles addition was also prepared using the same hot rolling conditions. In order to reveal the influence of the Ti particles on the interface structure of the Mg/Al composite sheets, a portion of them were annealed at 400 • C for 3 h and 10 h, respectively.

Mechanical Tests and Microstructure Measurement
The tensile mechanical performances of Mg and Al raw sheets, Mg/Al and Mg/Al-Ti composite sheets along the rolling direction (RD), and the transverse direction (TD) at room temperature were measured by a universal tester, and the tensile strain rate was 10 −3 s −1 . The samples for the tensile tests had a gauge length of 25 mm and width of 5 mm. Each tensile test was repeated three times.
The microstructure and element distribution near the interface of the composite sheets were characterized by a scanning electron microscope (SEM) that was equipped with energy dispersive spectroscopy (EDS). The samples for the SEM were mechanically ground with SiC sand papers, and the measured surface was the RD-ND plane. Inverse pole figure and

Mechanical Tests and Microstructure Measurement
The tensile mechanical performances of Mg and Al raw sheets, Mg/Al and Mg/Al-Ti composite sheets along the rolling direction (RD), and the transverse direction (TD) at room temperature were measured by a universal tester, and the tensile strain rate was 10 −3 s −1 . The samples for the tensile tests had a gauge length of 25 mm and width of 5 mm. Each tensile test was repeated three times.
The microstructure and element distribution near the interface of the composite sheets were characterized by a scanning electron microscope (SEM) that was equipped with energy dispersive spectroscopy (EDS). The samples for the SEM were mechanically ground with SiC sand papers, and the measured surface was the RD-ND plane. Inverse pole figure and pole figure were conducted on a Zeiss Gemini 300 SEM with the HKL Channel 5 system, and the measured surface was the RD-TD plane.

Microstructure
The SEM images and EDS mapping of the as-rolled composite sheets near the interface are shown in Figure 2. A good metallurgical bonding condition is clearly revealed in the Mg/Al and Mg/Al-Ti sheets after the hot rolling. There is no obvious diffusion layer close to the interface in these composite sheets. It can be seen that the Ti particles are uniformly distributed at the interface of the Mg/Al-Ti sheet (Figure 2d-f). Figures 3  and 4 show the SEM micrographs of the composite sheets after being annealed at 400 °C for 3 h and 10 h, respectively. After the annealing at 400 °C for 3 h, a thick diffusion layer (about 65 μm in thickness) can be clearly seen in the Mg/Al sheet (Figure 3a-c). An obvious thickening of the diffusion layer, with a thickness of about 120 μm, forms at the interface during the annealing at 400 °C for 10 h (Figure 4a-c). The high-magnification view further shows that the diffusion layer is composed of two sub-layers (Figures 3b  and 4b). The sub-layer close to the Al side is thicker than the sub-layer close to the Mg side. This transition layer structure is very common at the interfaces of Mg/Al composites during a hot process. Previous publications have shown that the sub-layer close to Al side is mainly composed of Mg2Al3, and that the sub-layer that is adjacent to the Mg side has abundant Mg17Al12 [8,36]. Cross-sectional micrographs of the Mg/Al-Ti sheet after the annealing at 400 °C for 3 h and 10 h are given in Figures 3d-f and 4d-f, respectively. It can be seen that the Ti particles addition can effectively reduce the quantity of the Mg-Al IMCs. However, compared to the annealed Mg/Al sheet, an obvious diffusion layer still formed in the region without the Ti particles addition to the Mg/Al-Ti sheet after the annealing, and the thickness of the diffusion layer does not obviously change. In addition, compared to the annealed Mg/Al sheet, the interface of the Mg/Al-Ti sheet is more likely to form holes after the annealing treatment, and these holes are mainly due to a certain degree of overburning of the Mg-Al IMCs during annealing at a high temperature.

Microstructure
The SEM images and EDS mapping of the as-rolled composite sheets near the interface are shown in Figure 2. A good metallurgical bonding condition is clearly revealed in the Mg/Al and Mg/Al-Ti sheets after the hot rolling. There is no obvious diffusion layer close to the interface in these composite sheets. It can be seen that the Ti particles are uniformly distributed at the interface of the Mg/Al-Ti sheet (Figure 2d-f). Figures 3 and 4 show the SEM micrographs of the composite sheets after being annealed at 400 • C for 3 h and 10 h, respectively. After the annealing at 400 • C for 3 h, a thick diffusion layer (about 65 µm in thickness) can be clearly seen in the Mg/Al sheet (Figure 3a-c). An obvious thickening of the diffusion layer, with a thickness of about 120 µm, forms at the interface during the annealing at 400 • C for 10 h (Figure 4a-c). The high-magnification view further shows that the diffusion layer is composed of two sub-layers (Figures 3b and 4b). The sub-layer close to the Al side is thicker than the sub-layer close to the Mg side. This transition layer structure is very common at the interfaces of Mg/Al composites during a hot process. Previous publications have shown that the sub-layer close to Al side is mainly composed of Mg 2 Al 3 , and that the sub-layer that is adjacent to the Mg side has abundant Mg 17 Al 12 [8,36]. Cross-sectional micrographs of the Mg/Al-Ti sheet after the annealing at 400 • C for 3 h and 10 h are given in Figures 3d-f and 4d-f, respectively. It can be seen that the Ti particles addition can effectively reduce the quantity of the Mg-Al IMCs. However, compared to the annealed Mg/Al sheet, an obvious diffusion layer still formed in the region without the Ti particles addition to the Mg/Al-Ti sheet after the annealing, and the thickness of the diffusion layer does not obviously change. In addition, compared to the annealed Mg/Al sheet, the interface of the Mg/Al-Ti sheet is more likely to form holes after the annealing treatment, and these holes are mainly due to a certain degree of overburning of the Mg-Al IMCs during annealing at a high temperature.
The microstructure and texture of the raw sheets and as-rolled composite sheets are shown in Figure 5. The results show that the raw Mg and Al sheets exhibit a fully recrystallized grain structure, with average grain sizes of about 9 µm and 22 µm, respectively. The raw Al sheet has a representative double texture, with <100> and <101> parallel to the ND (Figure 5a), and the raw Mg sheet exhibits a typical basal texture, with the basal poles being largely parallel to the ND ( Figure 5d). Obviously, compared to the raw sheets, both the Mg layer and Al layer of the as-rolled composite sheets have a much finer grain structure. As seen in Figure 5e,f, the Mg layers in the Mg/Al and Mg/Al-Ti sheets contain average grain sizes of 2.5 µm and 2 µm, respectively. The rolled Mg constituent still shows a typical basal texture, with most of its basal pole parallel to the ND, but some <0002> slightly incline toward the RD. However, the texture components of the Al constituent in the composite sheets change, exhibiting a representative double texture with <100> and <111> parallel to      Figure 6 shows crystallographic orientation maps of the Al layers in both the Mg/Al and Mg/Al-Ti sheets after being annealed at 400 • C for 3 h and 10 h. The annealed Al layers have a recrystallized microstructure containing a bimodal grain structure. Compared to the Al layer in the as-rolled composite sheets, the grain size of the annealed Al layers increases greatly. Obviously, the average grain size of the annealed Al layer in the Mg/Al sheets hardly change with the Ti particles addition. Compared to the rolled Al layer, the annealed Al layer exhibits a more random texture distribution. Similarly, the texture type of the annealed Al layer hardly changes with the Ti particles addition. Therefore, the above results show that the Ti particles addition has little impact on the grain size and texture type of the Al layer in the annealed Mg/Al composite sheet.   The microstructure and texture of the raw sheets and as-rolled composite sheets are shown in Figure 5. The results show that the raw Mg and Al sheets exhibit a fully recrystallized grain structure, with average grain sizes of about 9 μm and 22 μm, respectively. The raw Al sheet has a representative double texture, with <100> and <101> parallel to the ND (Figure 5a), and the raw Mg sheet exhibits a typical basal texture, with the basal poles being largely parallel to the ND (Figure 5d). Obviously, compared to the raw sheets, both the Mg layer and Al layer of the as-rolled composite sheets have a much finer grain structure. As seen in Figure 5e,f, the Mg layers in the Mg/Al and Mg/Al-Ti sheets contain average grain sizes of 2.5 μm and 2 μm, respectively. The rolled Mg constituent still shows a typical basal texture, with most of its basal pole parallel to the ND, but some <0002> slightly incline toward the RD. However, the texture components of the Al constituent in the composite sheets change, exhibiting a representative double texture with <100> and <111> parallel to the ND (Figure 5b,c). According to the above results, the Ti particles addition hardly affects the grain size and texture type of the as-rolled Mg/Al composite sheet.   Figure 7. After annealing at 400 °C for 3 h and 10 h, the grain size of the annealed Mg layers obviously increases, which have average grain sizes of about 13 μm and 14 μm (Figure 7a,b), respectively. In addition, the annealed Mg layers exhibit a typical basal texture of the rolled Mg sheet, with most of the basal poles being  Figure 7. After annealing at 400 • C for 3 h and 10 h, the grain size of the annealed Mg layers obviously increases, which have average grain sizes of about 13 µm and 14 µm (Figure 7a,b), respectively. In addition, the annealed Mg layers exhibit a typical basal texture of the rolled Mg sheet, with most of the basal poles being parallel to the ND (Figure 7a,b). As seen in Figure 7c,d, the grain sizes of the annealed Mg layers are about 13 µm and 14 µm, respectively. The annealed Mg layers also contain a similar basal texture to the rolled Mg sheet (Figure 7c,d). In consequence, the results show that the grain size and texture type of the annealed Mg layer in the Mg/Al sheets hardly influences by the Ti particles addition.
parallel to the ND (Figure 7a,b). As seen in Figure 7c,d, the grain sizes of the annealed Mg layers are about 13 μm and 14 μm, respectively. The annealed Mg layers also contain a similar basal texture to the rolled Mg sheet (Figure 7c,d). In consequence, the results show that the grain size and texture type of the annealed Mg layer in the Mg/Al sheets hardly influences by the Ti particles addition.  parallel to the ND (Figure 7a,b). As seen in Figure 7c,d, the grain sizes of the annealed Mg layers are about 13 μm and 14 μm, respectively. The annealed Mg layers also contain a similar basal texture to the rolled Mg sheet (Figure 7c,d). In consequence, the results show that the grain size and texture type of the annealed Mg layer in the Mg/Al sheets hardly influences by the Ti particles addition.

Mechanical Behavior
The tensile engineering stress-strain curves of the as-rolled composite sheets and the raw Al and Mg sheets, along the RD and TD, are given in Figure 8. Their mechanical properties are shown in Table 1. The Al 6082 sheet exhibits ultimate tensile strengths of 317 MPa and 313 MPa, and elongations of 13.4% and 12.6% during tension along the RD and TD, respectively. Compared to the 6082 sheet, the Mg AZ31 sheet has lower ultimate tensile strengths (about 249 MPa and 253 MPa) and much higher elongations (about 34.2% and 34.3%). As seen in Figure 8a and Table 1, the rolled Mg/Al-Ti sheet exhibits a lower ultimate tensile strength and elongation than the Mg/Al sheet. Obviously, the Ti particles addition slightly weakens the strength and elongation of the Mg/Al sheet. The main reason for this may be that the interface joint strength between the Mg and Al slightly decreases with the Ti particles addition.

Mechanical Behavior
The tensile engineering stress-strain curves of the as-rolled composite sheets a raw Al and Mg sheets, along the RD and TD, are given in Figure 8. Their mech properties are shown in Table 1. The Al 6082 sheet exhibits ultimate tensile streng 317 MPa and 313 MPa, and elongations of 13.4% and 12.6% during tension along t and TD, respectively. Compared to the 6082 sheet, the Mg AZ31 sheet has lower ul tensile strengths (about 249 MPa and 253 MPa) and much higher elongations 34.2% and 34.3%). As seen in Figure 8a and Table 1, the rolled Mg/Al-Ti sheet exh lower ultimate tensile strength and elongation than the Mg/Al sheet. Obviously, particles addition slightly weakens the strength and elongation of the Mg/Al shee main reason for this may be that the interface joint strength between the Mg a slightly decreases with the Ti particles addition.   Figure 9 shows the tensile engineering stress-strain curves of the Mg/A Mg/Al-Ti sheets after annealing along the RD and TD. Their mechanical propert given in Table 2. Compared to the as-rolled Mg/Al sheet, the ultimate tensile stren the annealed Mg/Al sheet is greatly reduced and the elongation shows a decr trend. In addition, with the increasing of the annealing time, the elongation of the sheet is decreased significantly. For instance, as seen in Figure 9b and Table 2, af nealing at 400 °C for 10 h, the elongations of the Mg/Al sheet tension along the R TD are only 13.4% and 12.0%, respectively. Previous studies have demonstrate   Figure 9 shows the tensile engineering stress-strain curves of the Mg/Al and Mg/Al-Ti sheets after annealing along the RD and TD. Their mechanical properties are given in Table 2. Compared to the as-rolled Mg/Al sheet, the ultimate tensile strength of the annealed Mg/Al sheet is greatly reduced and the elongation shows a decreasing trend. In addition, with the increasing of the annealing time, the elongation of the Mg/Al sheet is decreased significantly. For instance, as seen in Figure 9b and Table 2, after annealing at 400 • C for 10 h, the elongations of the Mg/Al sheet tension along the RD and TD are only 13.4% and 12.0%, respectively. Previous studies have demonstrated that these results might be mainly due to the formation of a large number of Mg-Al IMCs near the interface of the Mg/Al sheet after annealing [8]. However, the annealed Mg/Al-Ti sheet shows a higher UTS and E than the annealed Mg/Al sheet. The primary reason for this may be that the Ti particles can effectively inhibit the formation of Mg-Al IMCs during annealing. Obviously, as seen in Figures 3 and 4, the SEM results strongly support this speculation. Based on the above results, Ti particles addition can simultaneously improve the tensile strength and elongation of a composite sheet after annealing treatment.
these results might be mainly due to the formation of a large number of Mg-Al IMC the interface of the Mg/Al sheet after annealing [8]. However, the annealed Mg sheet shows a higher UTS and E than the annealed Mg/Al sheet. The primary reas this may be that the Ti particles can effectively inhibit the formation of Mg-Al during annealing. Obviously, as seen in Figures 3 and 4, the SEM results strongly su this speculation. Based on the above results, Ti particles addition can simultan improve the tensile strength and elongation of a composite sheet after annealing ment.   The tensile fracture micromorphologies of the as-rolled Mg/Al and Mg/Al-Ti are given in Figure 10. There is no severe peeling at the interface near the fracture s of the as-rolled Mg/Al and Mg/Al-Ti sheets (Figure 10a,b,e,f). It can be seen that particles are still clearly visible at the interface of the Mg/Al-Ti sheet (Figure 10e, tensile fracture surface of the rolled Al layer has abundant dimples, which shows cal ductile fracture (Figure 10c,g). As seen in Figure 10d,h, the fracture feature rolled Mg layer exhibits a large number of river patterns and some dimples, whi typical quasi-cleavage fracture morphology. A similar result has also been repor previous publications [37]. Obviously, the addition of Ti particles hardly affects th sile fracture feature of the as-rolled Mg/Al composite sheets.  The tensile fracture micromorphologies of the as-rolled Mg/Al and Mg/Al-Ti sheets are given in Figure 10. There is no severe peeling at the interface near the fracture surface of the as-rolled Mg/Al and Mg/Al-Ti sheets (Figure 10a,b,e,f). It can be seen that the Ti particles are still clearly visible at the interface of the Mg/Al-Ti sheet (Figure 10e,f). The tensile fracture surface of the rolled Al layer has abundant dimples, which shows a typical ductile fracture (Figure 10c,g). As seen in Figure 10d,h, the fracture feature of the rolled Mg layer exhibits a large number of river patterns and some dimples, which is a typical quasi-cleavage fracture morphology. A similar result has also been reported in previous publications [37]. Obviously, the addition of Ti particles hardly affects the tensile fracture feature of the as-rolled Mg/Al composite sheets. Figures 11 and 12 show the tensile fracture feature of the composite sheets that were annealed at 400 • C for 3 h and 10 h, respectively. As seen in Figures 11a,b and 12a,b, a severe debonding occurs near the fracture surface in the Mg/Al sheets, and the unilateral Al layer is obviously separate from the Mg layer. This phenomenon may be mainly attributed to the formation of a large number of Mg-Al IMCs near the interface of the Mg/Al sheet after annealing. Usually, a large number of brittle intermetallics, such as Mg 17 Al 12 and Mg 2 Al 3 , are easily formed at the interface of the Mg/Al composites after annealing. These brittle intermetallics are prone to cracking during loading, eventually resulting in a premature failure of the interface [18,20]. The tensile properties of the annealed Mg/Al sheets also confirm this result. As can be seen from  Figures 11 and 12 show the tensile fracture feature of the composite sheets that were annealed at 400 °C for 3 h and 10 h, respectively. As seen in Figures 11a,b and 12a,b, a severe debonding occurs near the fracture surface in the Mg/Al sheets, and the unilateral Al layer is obviously separate from the Mg layer. This phenomenon may be mainly attributed to the formation of a large number of Mg-Al IMCs near the interface of the Mg/Al sheet after annealing. Usually, a large number of brittle intermetallics, such as Mg17Al12 and Mg2Al3, are easily formed at the interface of the Mg/Al composites after annealing. These brittle intermetallics are prone to cracking during loading, eventually resulting in a premature failure of the interface [18,20]. The tensile properties of the annealed Mg/Al sheets also confirm this result. As can be seen from Figures 11e,f and 12e,f, some debonding also occurs at the interface near the fracture surface (Figure 11e,f), but the unilateral Al layer does not separate from the Mg layer, which is obviously different from the annealed Mg/Al sheet. This is mainly attributed to the addition of the Ti particles effectively inhibiting the formation of Mg-Al IMCs, enhancing the interfacial bonding strength of the composites, which greatly affects the tensile fracture mode of the Mg/Al sheets after annealing.
As seen in Figure 11c,d,g,h, the annealed Mg and Al layers of the composite sheets also exhibit a typical quasi-cleavage fracture and ductile fracture morphology, respectively. Interestingly, after being annealed at 400 °C for 10 h, the fracture feature of the Al layer exhibits much more river patterns and fewer dimples, which gradually changes from a ductile fracture to a quasi-cleavage fracture (Figure 12c,g). The Mg layer also shows a quasi-cleavage fracture feature (Figure 12d,h). Therefore, the annealing treatment can greatly affect the tensile fracture morphology of the Mg and Al layers in composite sheets. In the present study, the composite sheets, after being annealed at 400 °C for 10 h, have a thick diffusion layer with a thickness of about 120 μm. Generally, this thick diffusion layer is easy to crack during the loading, leading to a premature failure of the composite plate [18]. This is the reason why the fracture feature of the Al layer in the composite sheets changes after being annealed at 400 °C for 10 h. Therefore, according to the above results, the addition of Ti particles can greatly affect the tensile fracture mode of the Mg/Al sheets after annealing, but hardly changes the tensile fracture morphology of the Mg and Al components.

Conclusions
In the present study, Ti particles reinforced Mg AZ31/Al 6082 composite sheets were successfully prepared by hot rolling. The influence of Ti particles addition on the mechanical behavior and microstructure of Mg AZ31/Al 6082 composite sheets was systematically studied. Several conclusions were reached, and are as follows: (1) Ti particles are uniformly distributed at the interface of Mg/Al-Ti composite sheets, which can effectively restrain the formation of Mg-Al IMCs during annealing treatment. Compared to the annealed Mg/Al sheet, an obvious diffusion layer is still formed in the region without Ti particles addition to the Mg/Al-Ti sheet after annealing, but the thickness of this diffusion layer does not obviously change.
(2) Compared to the Mg/Al sheet, the Ti particles addition hardly affects the grain size

Conclusions
In the present study, Ti particles reinforced Mg AZ31/Al 6082 composite sheets were successfully prepared by hot rolling. The influence of Ti particles addition on the mechanical behavior and microstructure of Mg AZ31/Al 6082 composite sheets was systematically studied. Several conclusions were reached, and are as follows: (1) Ti particles are uniformly distributed at the interface of Mg/Al-Ti composite sheets, which can effectively restrain the formation of Mg-Al IMCs during annealing treatment. Compared to the annealed Mg/Al sheet, an obvious diffusion layer is still formed in the region without Ti particles addition to the Mg/Al-Ti sheet after annealing, but the thickness of this diffusion layer does not obviously change.
(2) Compared to the Mg/Al sheet, the Ti particles addition hardly affects the grain size As seen in Figure 11c,d,g,h, the annealed Mg and Al layers of the composite sheets also exhibit a typical quasi-cleavage fracture and ductile fracture morphology, respectively. Interestingly, after being annealed at 400 • C for 10 h, the fracture feature of the Al layer exhibits much more river patterns and fewer dimples, which gradually changes from a ductile fracture to a quasi-cleavage fracture (Figure 12c,g). The Mg layer also shows a quasi-cleavage fracture feature (Figure 12d,h). Therefore, the annealing treatment can greatly affect the tensile fracture morphology of the Mg and Al layers in composite sheets.
In the present study, the composite sheets, after being annealed at 400 • C for 10 h, have a thick diffusion layer with a thickness of about 120 µm. Generally, this thick diffusion layer is easy to crack during the loading, leading to a premature failure of the composite plate [18]. This is the reason why the fracture feature of the Al layer in the composite sheets changes after being annealed at 400 • C for 10 h. Therefore, according to the above results, the addition of Ti particles can greatly affect the tensile fracture mode of the Mg/Al sheets after annealing, but hardly changes the tensile fracture morphology of the Mg and Al components.

Conclusions
In the present study, Ti particles reinforced Mg AZ31/Al 6082 composite sheets were successfully prepared by hot rolling. The influence of Ti particles addition on the mechanical behavior and microstructure of Mg AZ31/Al 6082 composite sheets was systematically studied. Several conclusions were reached, and are as follows: (1) Ti particles are uniformly distributed at the interface of Mg/Al-Ti composite sheets, which can effectively restrain the formation of Mg-Al IMCs during annealing treatment. Compared to the annealed Mg/Al sheet, an obvious diffusion layer is still formed in the region without Ti particles addition to the Mg/Al-Ti sheet after annealing, but the thickness of this diffusion layer does not obviously change.
(2) Compared to the Mg/Al sheet, the Ti particles addition hardly affects the grain size and texture type of the Mg layer and Al layer in the Mg/Al-Ti sheet, before and after annealing. The rolled and annealed Mg layers always exhibit a typical basal texture, with the basal poles being largely parallel to the ND. The rolled Al layer shows a representative double texture, with <100> and <111> parallel to the ND, but the annealed Al layer exhibits a more random texture distribution. (3) The annealed Mg/Al-Ti sheet shows a higher tensile strength and elongation than the annealed Mg/Al sheet, which reveals that the Ti particles addition can simultaneously improve the tensile strength and elongation of the composite sheet after annealing treatment. Compared to the Mg/Al sheet, the Ti particles addition hardly affects the tensile fracture morphology of the Mg layer and Al layer in the Mg/Al-Ti sheet before and after annealing.