Mechanical Properties Of Mg Research Articles

Recent advances in mechanical properties of Mg matrix composites: a review

Magnesium (Mg), with a density of two-thirds of aluminium (Al) and one-fourth of steel, has become one of the most attractive materials for automotive and aerospace industries owing to the obligation to reduce fuel consumption and gas emissions. However, the poor mechanical property of Mg is one of the most significant barriers to its widespread use. The most widely used method to increase the use potential of Mg is the development of Mg matrix composites. This review focuses on the mechanical properties of recent Mg matrix composites. The effect of different reinforcement materials on the mechanical behaviour and failure mechanisms of Mg matrix composites was evaluated in detail.

Improvement of microstructures and mechanical properties of Mg–3Zn-0.5Zr by friction stir processing

Friction stir processing (FSP) has been applied to improve the microstructure and tensile performance of as-cast Mg–3Zn-0.5Zr magnesium alloy. By FSP, grains within the stir zone (SZ) demonstrate noticeable refinement and the varied processing parameters can lead to the formation of both strong and weak textures within the SZ. Second-phase particles are broken down, dispersed, and partially re-dissolved. In addition, optimal processing parameters lead to enhanced uniformity in refined grains and increased dispersion of secondary-phase particles, resulting in improved both in microhardness and tensile properties. The sample processed at 800-200 (rpm/mm∙min−1) demonstrates an overall improvement in tensile properties compared to the base material, with yield strength, ultimate strength, and uniform elongation of 93.7 MPa, 215.0 MPa, and 25.4%, respectively.

Effect of extrusion ratio on microstructure, texture, and mechanical properties of dual-phase Mg−8Li−6Zn−2Gd alloy

The microstructure observation, macrotexture analysis, and tensile test were conducted to investigate the effect of extrusion ratio on the microstructure, texture, and mechanical properties of Mg−8Li−6Zn−2Gd alloy. The results show that the as-homogenized Mg−8Li−6Zn−2Gd alloy consists of α-Mg, β-Li, MgLiZn, I-phase, and W-phase. After hot extrusion, eutectic I-phase is broken into fine particles, while W-phase maintains massive shape. Both α-Mg and β-Li matrices undergo dynamic recrystallization (DRX), and their grains gradually refine with increasing extrusion ratio. For α-Mg matrix, the weakening of basal texture and the strengthening of prismatic texture after hot extrusion are due to the activation of non-basal slip. For β-Li matrix, the appearance of obvious α and γ fiber textures after hot extrusion is associated with the dynamic recovery (DRV) and DRX. The tensile strength and elongation of the alloy are simultaneously improved by hot extrusion, and the best comprehensive mechanical properties are achieved when extrusion ratio is 16:1.

A Rolled Mg–8Al–1Sm–1Zn Alloy with High‐Strength Ductility via Single‐Pass Liner Rolling

In this article, the microstructure and mechanical properties of Mg–8Al–1Sm–1Zn alloy prepared by multi‐pass conventional rolling and single‐pass liner rolling are investigated. The alloy is subjected to multi‐pass conventional rolling with a cumulative deformation of 60% and single‐pass liner rolling with a deformation of 60% after solution‐treated (T4 temper) at 400 °C, respectively. In the results, it is shown that the best mechanical properties are obtained by single‐pass liner rolling at 400 °C with a deformation of 60% deformation under the combined effect of grain refinement and precipitation strengthening. The average grain size of the alloy is 7.2 μm and the microhardness is 80 HV. The tensile yield strength, ultimate tensile strength, and elongation at room temperature are 255 MPa, 285 MPa, and 12.7%, which are 14.9%, 15.3%, and 10.4% higher than those of the conventional multi‐pass rolled alloy, respectively.

Microstructure and mechanical properties of Mg–Li alloys fabricated by wire arc additive manufacturing

Gas tungsten arc welding (GTAW) based wire arc additive manufacturing (WAAM) process is first used to fabricate a thin wall of LA103Z magnesium-lithium alloy. Results indicate that the grain size of the LA103Z thin-walled bottom region significantly differs from that of the middle and top regions. The main phases present in the LA103Z thin wall include α-Mg and β-Li phases, along with some particulate second phases (LiAl, Li2MgAl). Moreover, the thermal action of the subsequent sedimentary layer promotes the transformation of β-Li→α-Mg+β-Li and Li2MgAl →LiAl phase. The mechanical properties of the LA103Z thin wall are affected by a combination of factors such as grain size, the proportion of the α-Mg phase, and morphology. The tensile strength of the LA103Z thin-walled samples in the bottom, middle, and top regions is measured at 195.1 MPa, 181.8 MPa, and 201.4 MPa, respectively, with corresponding elongation percentages of 3.4%, 7.3%, and 12.4%. In the building direction, the tensile strength is recorded as 177.7 MPa, with an elongation percentage of 7%. The study reveals that WAAM-GTAW has the potential to make magnesium-lithium alloys more widely available.

Effect of La2O3 on Microstructure and Mechanical Properties of Mg–3Y Alloy

Effect of La2O3 on Microstructure and Mechanical Properties of Mg–3Y Alloy

Effect of Ca addition on microstructure and mechanical properties of Mg–3.8Al–1.1Sn alloys

Effect of Ca addition on microstructure and mechanical properties of Mg–3.8Al–1.1Sn alloys

Effect of deformation processing on microstructure evolution and mechanical properties of Mg−Li alloys: A review

As the lightest structural metal, Mg−Li alloys, possessing the advantages of high specific strength, high specific stiffness, good electromagnetic shielding, and damping properties, have a bright application prospect in automotive, aerospace, transportation, medical and other fields. However, the strength of Mg−Li alloys is lower when compared to other structural metals, which requires alloying or deformation treatment to enhance mechanical properties. The research progress of deformation processing of Mg−Li alloys is summarized, including the effect of conventional plastic deformation and severe plastic deformation on the microstructure and mechanical properties of Mg−Li alloys, the effect of strain and temperature in the deformation process on their microstructure and mechanical properties, and several grain refinement mechanisms of Mg−Li alloys. The problems encountered during the industrial application of Mg−Li alloys are discussed. Grain refinement and enhanced work hardening are still the primary means to improve the comprehensive performance. Several structural design strategies (heterogeneous structured materials) are highlightened, which will be helpful for the guidance of future innovations for Mg−Li alloys to reach high strength.

Enhancing the mechanical properties of Mg–Al alloy by introducing Al2Y nanoparticles via rapid-cooling solidification and optimized heat treatments

Coarse grain and poor thermal stability of Mg17Al12 are usually present in the as-cast Mg–Al alloys, which are detrimental to the mechanical properties. In this work, the microstructure evolution, and mechanical properties of as-cast AZ31-1Y alloy with different cooling rates (4.0–29.9 °C/s) were systematically investigated by thermal analysis and microstructure characterization. The results show that the addition of Y to AZ31 alloy results in the formation of primary Al2Y and eutectic Al2Y, while suppressing the formation of β-Mg17Al12. The AZ31-1Y alloy with a cooling rate of 29.9 °C/s exhibits the finest grain, with a grain refinement efficiency 40.9 % higher than that of AZ31 alloy with a cooling rate of 4.0 °C/s. After heat treatment, the acicular eutectic Al2Y is modified into a granular shape and numerous nano-sized Al2Y precipitates are observed within the α-Mg matrix. The addition of Y can effectively improve the mechanical properties of AZ31 alloy under high cooling rates, but the mechanical properties deteriorate at slower cooling rates due to stress concentration caused by the agglomeration of large-sized Al2Y particles. The optimal mechanical properties of the AZ31-1Y alloy are achieved at a cooling rate of 29.9 °C/s combined with subsequent heat treatment, and its YS, UTS, and EL reached up to 69 MPa, 293 MPa, and 14.5 %, respectively. Moreover, the related strengthening mechanisms are quantified. It is believed that this work can provide guidance for controlling the microstructure and optimizing the mechanical properties of as-cast Mg–Al alloys.

Exploring the effect of bimodal microstructure on the mechanical properties of Mg–15Er binary alloy by regulating the extrusion ratio

Bimodal-grained Mg–Gd alloys exhibits excellent mechanical strength due to the high solid solubility of Gd element, which facilitates the strong precipitation strengthening. Er element has a higher solid-solubility than Gd in Mg, which may have a great potential in achieving high strength for Mg alloy. In the study, the Mg–15Er alloy with bimodal microstructure of different proportion of two components is fabricated by adjusting the extrusion ratio and microstructures and mechanical properties for the bimodal-structured Mg–15Er alloy are systematically investigated. The results suggest that the ErH2 phase in the Mg–15Er alloys is stable, regardless of the casting state, solid solution state, or extrusion state. Only a small number of dynamic precipitates is formed during extrusion due to the high solid solubility of Er in Mg. Moreover, the formation of dynamic precipitated MgEr3 phase, where the number of Er atoms is greater than that of Mg atoms, also leads to the inability to form high-density precipitates. The larger extrusion ratio results in higher volume fraction of dynamic recrystallization (from 24 % to 89 %), and larger grain size (from 4.1 μm to 7.9 μm). The results show that the ultimate tensile strength decreases from 301 MPa to 235 MPa, and the elongation increases from 12.5 % to 23.5 % with the increase of the extrusion ratio, which are primarily related to the components of unrecrystallized grains and recrystallized grains rather than dynamic precipitates.

Insights into the evolution of texture and mechanical properties during warm rolling and annealing of Mg–2Zn-0.5Ca alloy

In this work, we systematically investigated the microstructure, texture evolution and mechanical properties of Mg–2Zn-0.5Ca alloy during warm rolling and annealing. The results showed that the net-like Mg6Zn3Ca2 secondary phases are evolved into short wire-like and fragmented into smaller pieces with the increasing rolling reduction. Besides, some recrystallization grains can be generated with a higher rolling reduction, resulting in a significant grain refinement, which is prone to suppress the activation of twinning. The formation of a double-peak texture with basal poles splitting from the normal direction (ND) towards the transverse direction (TD) can be mainly ascribed to the prismatic <a> slip during warm rolling. The formation of TD-oriented recrystallized grain leads to a transformation from a broadening of angular distribution towards the rolling direction (RD) to a broadening of angular distribution towards the TD. Moreover, the yield strength is dramatically enhanced by the synergetic strengthening effect of grain refinement, work hardening, and texture evolution. After annealing, the sample with high rolling reduction can achieve a combination of high yield strength and high formability due to the fine grains structure containing massive precipitates, which is also featured by an elliptical shape texture with basal poles inclining towards RD and TD.

Microstructure, texture, and mechanical properties of Mg–4Zn–1Mn–xCa alloys and the fabrication of biomedical Mg thin-walled micro-tubes

Microstructure, texture, and mechanical properties of Mg–4Zn–1Mn–xCa alloys and the fabrication of biomedical Mg thin-walled micro-tubes

Microstructure evolution and mechanical properties of Mg–Mn–RE alloy processed by equal channel angular pressing

Equal Channel Angular Pressing (ECAP) has been used to successfully produce ultrafine-grained ME21 alloy with a good strength-ductility synergy. The microstructure of the as-cast ME21 alloy and its evolution during the ECAP processing were characterized using a combination of optical microscopy (OM) and scanning electron microscopy (SEM). Fracture surfaces after tensile test were also characterized using SEM. Chemical analysis and phase identification were done by energy dispersive spectroscopy (EDS) and X-ray diffraction analysis, respectively. The combination of these techniques enabled the interpretation of the mechanical behavior during the various processing stages of the alloys. The ECAP process was performed up to 16 passes, producing a uniform ultra-fine grain (1 µm) ME21 alloy resulting from full dynamic recrystallization. At room temperature, the yield strength after 16 ECAP passes (191.4 MPa) was 251% higher than that of the as-cast ME21 alloy, accompanied by a good elongation of 8.1%. The hardness increased to 60.7HV which is about 52% higher than that of the as-cast alloy. These improvement in mechanical properties is due to the ultra-fine grains with high angle grain boundaries (HAGBs) and the precipitate strengthening effects of the uniformly dispersed fine precipitates of Mg12Ce and Mn formed as a result of the intense shear during the ECAP process.

Exploring the influence of cosegregation on mechanical properties of Mg [formula omitted] twin boundaries: A first-principles investigation

This study employs first-principles calculations to investigate the impact of solute segregation on the mechanical properties of the Mg twin boundary (TB). The investigation delves into single-element segregation and multielement cosegregation at the Mg{101¯1} twin boundary. Several parameters, including segregation energy, solubility energy, and strengthening/embrittlement energy, are determined, and Voronoi volume and electronic structure evolution are analyzed. The study discloses the effects of 21 solute single-segregation, as well as the segregation mechanism of Ca, Y, and Zn solute elements in paired combinations. A comparative assessment of the optimal combination for cosegregation of Ca/Y atoms with larger atomic radii and Zn atoms with smaller atomic radii reveals that the solute elements Ca and Y induce more robust energy changes at the interface segregation than Zn. Additionally, electronic structure analysis suggests that charge transfer between solute atoms with large atomic radii and solute atoms with small atomic radii can strengthen the chemical bond at the twin boundary, thereby enhancing the maximum tensile degree, ductility, and formability of the material. The outcomes of this investigation have significant theoretical implications for composition design and the development of novel high-performance multielement magnesium alloys.

Effect of transverse gradient extrusion process on texture and mechanical properties of Mg–3Al–1Zn alloy sheets

Transverse gradient extrusion (TGE) processes with different die inclined angles of 15°, 30°, 45°and 60° were used to produce Mg–3Al–1Zn sheets, thereby tailoring texture and mechanical properties of Mg alloy sheets. Microstructure, deformation texture and final mechanical properties of the obtained sheets were detected and discussed. Furthermore, the rheological behavior of Mg alloys during extrusion was analyzed by finite element method. As the TGE die inclined angle changed, the flow velocity along the transverse direction (TD) and effective strain difference along extrusion direction (ED) were changed during extrusion, and therefore the microstructure and texture of extruded sheets are altered. With increase of TGE die inclined angles, fine grain size and uniform microstructure were obtained. The base poles of most grains for the extruded sheets gradually deviate from normal direction (ND) to ED at center region and inclined from ED to TD at 1/4 edge region. A large elongation of 33.9 % and a low yield stress of 125 MPa can be obtained in the TGE-45 sheet.

Effect of pre-compression deformation on aging precipitation behavior and mechanical properties of Mg–5Sn alloy

The study aimed to investigate the impact of different aging time and the compression prior to aging on the precipitation behavior and mechanical properties of the Mg–5Sn(wt.%) alloy. The findings revealed that compression prior to aging significantly reduced the time required to reach peak aging and resulted in a higher peak hardness, reaching up to 63 H V after 5 h of aging. The pre-compression introduced dislocation densities of up to 1.916 × 1015/m2, creating more nucleation sites for precipitated phases. As a result, pre-compression aging led to an order of magnitude more precipitated phases compared to direct aging. Interestingly, the study also discovered that hardness and strength did not exhibit a traditional positive correlation. The maximum strength was not achieved when hardness reached its peak. The increased numbers of precipitated phases were closely associated with an increase in strength but did not always enhance the corresponding hardness. The deviation of the hardness along with the increased precipitated phases was mainly imputed to the softening of the precipitated phases themselves. These findings highlight the complex relationship between hardness, strength, and the microstructures of the Mg–5Sn alloy during pre-compression and aging treatment.

Effects of B4C on the formation of LPSO phase and mechanical properties of Mg–Zn–Y–Mn alloy

Effects of B4C on the microstructure and properties of Mg94Zn2.5Y2.5Mn1 alloy were investigated by means of optical microscope, scanning electron microscope, X-ray diffraction, transmission electron microscope, nano indentation tester and electronic universal testing machine. The results indicated that the as-cast Mg94Zn2.5Y2.5Mn1 alloy was mainly composed of α-Mg, fishbone-like W phase, and block 18 R long period stacking ordered (LPSO) phase. The addition of an appropriate amount of B4C could effectively refine grains, promote the formation of the LPSO phase and inhibit the generation of the W phase. The microstructure and mechanical properties of the alloy were both optimal at the addition of 0.5 at.% B4C. The microstructure exhibited a refined grain size from 41.2 μm to 20.7 μm, and the volume fraction of the LPSO phase increased from 8.1 % to 22.5 %. The yield strength increases from 112 MPa to 145 MPa, the tensile strength of the alloy was enhanced from 192 MPa to 256 MPa, and the elongation increased from 4.8 % to 8.6 %.

Investigation of the microstructure and mechanical properties of Mg–Al–Zn alloy joints formed by different laser welding processes

Abstract The microstructure and mechanical properties of Mg–Al–Zn alloy joints by using autogenous laser beam welding (LBW) and laser-MIG hybrid welding, respectively, are investigated. The results show that the weld formation of the hybrid welding joint is relatively good, and there are mainly α-Mg matrix phases and β-Mg17Al12 strengthening phases in the weld metal. The microstructure in the fusion zone (FZ) of the two joints is different. The LBW joint is composed of columnar crystal and equiaxed dendrite. The hybrid welding joint consists of fine equiaxed grains, and the grain size in the laser zone is larger than that in the arc zone. The microhardness in FZ is higher due to the precipitation of the β-Mg17Al12 phase in this region. Under the optimized welding procedure, the strength coefficient of the two joints is &gt;90%. There are many dimples on the tensile fracture surface of the hybrid welding joint, which is characterized by the pattern of the ductile fracture.

Influence of Gd and Li additions on the microstructural evolution and mechanical properties of hot-rolled AZ31 alloy

Thermomechanical processing and alloying are two common approaches to enhance the mechanical properties of Mg. Thus, the effects of Gd and Li elements, as two elements with various properties, on the microstructure and mechanical properties of a hot-rolled and consequently annealed AZ31 alloy were analyzed. The microstructure and texture was analyzed by scanning electron microscopy and electron back scattered diffraction. Accordingly, the mean grain size of 46 μm in the AZ31 alloy was reduced to 41 and 26 μm in the AZ31–2.9Gd and AZ31–2.3Li alloys, respectively. Grain refinement occurred due to continuous dynamic recrystallization and twinning-induced recrystallization in all of the alloys. Textural evolution showed that neither Gd nor Li could inhibit the occurrence of basal texture. Room temperature mechanical properties were assessed by using the shear punch test (SPT) method. The results exhibited that the strength of the AZ31 alloy was improved from 116 MPa to 139 MPa and 141 MPa by respective additions of Gd and Li. Strength enhancement was mainly attributed to the grain boundary strengthening and second-phase particles hardening. One promising observation was the simultaneous enhancement of shear strength and ductility by the addition of Gd and Li. This observation was ascribed to the more uniform distribution of second-phase particles and lower volume fraction of twins as potential sites for crack initiation. As long as mechanical strength is concerned, results favor the use of Li as alloying element in Mg, especially due to the more noticeable lightweighting potential compared to Gd.

Effect of Ti particles on microstructure and mechanical properties of Mg–9Al–1Zn based composite sheets

It is a great challenge to simultaneously improve the strength and ductility of magnesium matrix composites (MMCs). In this work, AZ91 alloys reinforced with 1 wt%, 2 wt%, and 3 wt% Ti particles were produced using stir casting combined with ball milling process. The microstructure of the extruded composite sheets was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), electron backscatter diffraction (EBSD). Transmission electron microscopy (TEM) was utilized to observe the structure of the Ti/Mg interface. The mechanical properties of the composite sheets were also investigated. The results show that the adding Ti particles, the texture strength decreased, and the growth of recrystallization grains was also restrained. Due to the interfacial reaction between Ti and Al, the formation of β-phase (Mg17Al12) was inhibited. The tensile test demonstrated that the Ti particles could significantly improve the mechanical properties of the AZ91 alloy sheets. Compared to AZ91 sheet, 2Ti/AZ91 composite sheet along extrusion direction (ED) showed the best comprehensive mechanical properties. The improvement in mechanical properties was mainly attributed to grain refinement, texture weakening, mismatched coefficient of thermal expansion (CTE), and work hardening.