Microstructures and mechanical properties of as-ECAPed Mg–8Sn alloys with the combined addition of Zn and Al

Abstract

A "RE-free" and I-phase-containing Mg-8Sn-based alloy system was developed and successfully fabricated through the equal channel angular pressing (ECAP) process. The influence of the Zn/Al mass ratio on the microstructures and mechanical properties of the as-ECAPed Mg-8Sn-(5,6,7) Zn-2(wt%)Al alloys was investigated using an optical microscope, an X-ray diffractometer, a scanning electron microscope, a transmission electron microscope, and a universal testing machine. Grain size, dynamic recrystallization behavior, and texture were found to be greatly affected by the Zn/Al mass ratio. Furthermore, the ultimate tensile strength (250 MPa) and elongation (14.5%) of the alloy with a Zn/Al mass ratio of 3 were considerably increased compared to those of the as-ECAPed alloys with Zn/Al ratios of 2.5 and 3.5 (ultimate tensile strength and elongation of 215 MPa and 13% and 184 MPa and 10%, respectively). This significant enhancement was attributed to extensive grain boundary strengthening, precipitation strengthening, and higher work hardening capacity as well as texture randomization. The strength and ductility of the as-ECAPed alloys are also discussed in terms of the I-phase and Mg 2 Sn formation.

Enhancement of resistance to galvanic corrosion of ZE41 Mg alloy by equal channel angular pressing

“…The equiaxed UFG microstructure with an average grain size of 15 µm resulted from dynamic recrystallization and is apparent from the optical image of 6th pass ECAP represented in Figure d. A similar kind of UFG refinement has been reported by different researchers . The grain refinement obtained is in good agreement with one of the grain refinement models proposed by Figueiredo and Langdon .…”

“…A similar kind of UFG refinement has been reported by different researchers. [19,20,29] The grain refinement obtained is in good agreement with one of the grain refinement models proposed by Figueiredo and Langdon. [30] A two-step ECAP strategy was adopted in this study to achieve enhanced improvement in mechanical properties namely, yield strength, percent elongation as well as ultimate tensile strength suggested by various researchers.…”

Influence of Equal Channel Angular Pressing Passes on the Microstructures and Tensile Properties of Mg-8Sn-6Zn-2Al Alloy

“… Hall-Petch relation of the Mg–Sn alloy having undergone ECAP as calculated from this paper and our previous results (reference [ 10 , 32 ]). …”

“…In general, the constant term ( σ 0 ) and slope ( k ) in the Hall-Petch relationship can be influenced by the variation of the texture intensity in Mg alloys [ 31 ]. Thus, in order to comprehensively considering the combined effect, based on our previous work [ 10 , 32 ] and the present research, an amendatory Hall-Petch equation suitable for the Mg–Sn–Zn–Al alloys that undergone ECAP with a maximum texture intensity of less than 4 was established as following: σ = 313.8· d −1/2 + 14.7. The results are shown in Figure 10 .…”

Microstructure and mechanical property of high strength Mg–Sn–Zn–Al alloys

“…Much work so far has been devoted to Mg-Sn-Zn-Al wrought alloys. The basic thought for researching is that ingots are subject to solid solution treatment, hot deformation and reasonable heat treatments to refine the grains and precipitates [9][10][11]. Certainly, supplementary methods such as pre-deformation [12], preaging [13] and complex aging treatments [14,15] are useful in further enhancing the mechanical property.…”