Effect of Heat Treatment on Microstructure and Mechanical Properties of Mg-5Zn-1Mn Alloy Tube

Abstract

The effects of heat treatment on the microstructure, mechanical properties and electrochemical property of the as-extruded Mg-5Zn-1Mn (ZM51) alloy tube are investigated by optical microstructure (OM), X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electrical microscope (TEM), uniaxial tensile test, and electrochemical test. The results show that the as-cast structure is a typical dendritic structure, mainly composed of α-Mg and Mg7Zn3 eutectic compounds. After homogenization, most of Mg7Zn3 eutectic phases are dissolved in the Mg matrix. During the extrusion process, the ZM51 alloy has undergone complete dynamic recrystallization and has a good elongation, reaching 21.4%. T6, especially T4 + double aging treatment, can significantly improve the mechanical properties of the as-extruded tube. The microstructure reveals that the precipitation strengthening of the finely dispersed MgZn2 precipitates is the main reason for the strength increase. The fracture micromorphology of the as-extruded tube is mainly composed of dimples and cleavage facets, which is a typical ductile fracture. The fracture mode of the as-aged alloy tubes belongs to cleavage fracture. In addition, the electrochemical test results show the solution-treated ZM51 alloy tube has the best corrosion resistance. The improvement of corrosion resistance is mainly due to the microstructure uniformity and low phase volume fraction.

Effects of annealing temperature on microstructure and mechanical properties of LZ91 alloy

“…Li et al. [37] marked that the Mg–5Zn–1Mn alloy with fully dynamic recrystallization had the EL of 21.4%. Sun et al.…”

“…Pourbahari et al [36] also stated that the grain refinement significantly improved the strength and ductility of the alloy. Li et al [37] marked that the Mg-5Zn-1Mn alloy with fully dynamic recrystallization had the EL of 21.4%. Sun et al [38] processed nickel base alloy with the YS, UTS and microhardness increased by 475%, 130% and 180% through severe cold rolling process, and the grain size was greatly refined after annealing at 600 and 700°C.…”

Corrosion Behavior in Magnesium-Based Alloys for Biomedical Applications

“…T6 treatment, also known as precipitation heat treatment, involves the use of a solution treatment at high temperatures and subsequent artificial aging [ 242 ]. T6 produces a slightly lower corrosion resistance than T4, as the precipitates enhance galvanic couples [ 169 , 246 ]. Given the dual influence of secondary phases in corrosion, such precipitates may also provide further corrosion resistance.…”

“…Given the dual influence of secondary phases in corrosion, such precipitates may also provide further corrosion resistance. Li et al, investigated the effects of heat treatments on microstructure and corrosion resistance in Mg–5Zn–1Mn alloy tubes [ 246 ]. Although the resistance of T6-treated ZM51 alloys was lower than that of T4-treated alloys, it was superior to that of extruded samples.…”

A Quasi In-Situ Study on the Microstructural Evolution of 2195 Al-Cu-Li Alloy during Homogenization

“…The microstructural evolution of these ingots during homogenization has a significant impact on their deformation, recovery and recrystallization behaviors in subsequent processes, such as rolling and forging [ 15 , 16 , 17 , 18 , 19 , 20 ]. For example, T B and θ phases on the grain boundaries will dissolve in the appropriate homogenization process, thus inhibiting the initiation of cracks during subsequent processing [ 21 , 22 ] and improving their mechanical properties after aging [ 23 , 24 , 25 ]. Therefore, an in-depth investigation of the microstructural evolution during the homogenization of Al-Cu-Li alloys is significant for understanding their material properties and optimizing subsequent processing.…”