Mechanical Properties Of As-extruded Mg Research Articles

Hot deformation behavior and extrusion temperature-dependent microstructure, texture and mechanical properties of Mg–1Mn alloy

Mg–1Mn alloy, extruded at a low temperature in our published protocol, contributed to the intensified basal texture and extremely refined microstructure with spheroidal nanoscale precipitates dispersing throughout the matrix and along the grain boundaries, consequently resulting in the excellent mechanical properties where the alloy exhibited a tensile yield strength of 204.3 MPa and a ductility of 38.8% at room temperature. Therefore, Mg–1Mn alloy was recommended as one of the potential materials for structural applications. In the present investigation, hot deformation behavior through constitutive analysis and extrusion temperature-dependent microstructure, texture and mechanical properties of as-extruded Mg–1Mn alloy were investigated, aiming at revealing how extrusion temperature affected microstructure, texture, and mechanical properties of as-extruded Mg–1Mn alloy. X-ray diffraction patterns demonstrated that phase components of the experimental alloys consisted of the α-Mg matrix and Mn precipitates. Optical microscopy images indicated a significant increase in average grain size of the alloys as the extrusion temperature increasing from 250 °C to 400 °C. Scanning electron microscopy graphics revealed that coarsened particles identified as Mn precipitates by EDS were observed within the matrix when extrusion temperature reached 400 °C. Inverse pole figure maps of the experimental samples subjected to different extrusion temperatures in the present work exhibited the typical basal texture, suggesting that basal slip was activated hardly during the tensile stress applied along the extrusion direction. Consequently, extrusion temperature displayed the significant impact on microstructure, texture, and mechanical properties of as-extruded Mg–1Mn alloy. The alloy extruded at both 250 °C and 300 °C exhibited the strong basal texture and refined microstructure with spheroidal nanoscale precipitates dispersing within the matrix and along the grain boundaries, which contributed to their excellent comprehensive mechanical properties. The alloy extruded at 400 °C possessed the typical basal texture and coarsened microstructure, leading to the extremely poor mechanical properties. Simultaneously, the constitutive model of the Arrhenius equation based on Zener-Hollomon parameters was also established in the present investigation. Therefore, optimizing the extrusion temperature to regulate the microstructure, grain orientation distribution, and morphology of precipitates was considered as one of the effective approaches for achieving the excellent mechanical properties of Mg alloys.

Rapid corrosion rates and high mechanical properties of as-extruded Mg–Er–Ni alloys by introducing LPSO and γʹ phases

The Mg–Er–Ni alloy with comparable strength and solubility was prepared by controlling the Ni content. The mechanical properties and corrosion mechanism of alloys with long-period stacking ordered (LPSO) phase, as well as those with both LPSO and γʹ phases, were investigated and clarified. This study focused on investigating the underlying reasons for the high mechanical strength and fast corrosion rate of the Mg–13Er–3Ni alloy with LPSO and γʹ phases. The highest corrosion rate of the Mg–13Er–3Ni (wt.%) alloy is not only associated with the high volume fraction of the LPSO phase, which provides a larger zone for the corrosion cathode rather than forming a corrosion barrier, but also linked to the introduction of the γʹ phase that forms new sites for galvanic corrosion and avoids the formation the Er2O3 corrosion product film with corrosion-resistant. Moreover, The high mechanical properties of Mg–13Er–3Ni alloy are mainly attributed to the texture strengthening, dislocation strengthening and the second phase reinforcement that were caused by high volume fraction of LPSO phase and the precipitation of lamellar γʹ phase in Mg matrix. Generally, Compared to the Mg–13Er-1.5Ni (wt.%) alloy, the corrosion rates and mechanical strength of Mg–13Er–3Ni (wt.%) alloy were increased significantly by 302.8% and 50.3%, respectively, by coupling the LPSO and γʹ phases. Its ultimate tensile strength of 445 MPa and corrosion rare of 128.5 mg cm−2 h−1, which provides a new high strength and rapid corrosion Mg alloy materials for fracturing tools application.

Effects of Sn and Mn Addition on the Microstructure and Mechanical Properties of As-Extruded Mg–2Al–1Zn Alloys

Effects of Sn and Mn Addition on the Microstructure and Mechanical Properties of As-Extruded Mg–2Al–1Zn Alloys

Effects of Al on microstructure and mechanical properties of hot-extruded Mg–3Nd alloys

The effects of Al content on microstructure, texture, and mechanical properties of as-extruded Mg–3Nd alloy were investigated. The particle stimulated nucleation effect of Al2Nd and Al11Nd3 phases promotes dynamic recrystallisation and the texture is weakened of the as-extruded alloys. With the increase in Al content in the alloys, the microstructure transformed from a bimodal structure to an almost fully recrystallised structure. Grain refinement, the distribution of the second phases, and texture are important factors determining the mechanical properties of as-extruded alloys. As-extruded Mg–3Nd–3Al achieved a good balance of strength and plasticity. The ultimate tensile strength, yield strength, and elongation are 283, 221.3 MPa, and 15.7%, respectively.

Microstructures and mechanical properties of as-extruded Mg–8Gd–2Y–1Zn–6Li alloy

In this study, a high-performance Mg–8Gd–2Y–1Zn–6Li (wt%) alloy having a TYS of 202 ± 2.6 MPa, UTS of 243 ± 2.1 MPa and EL of 10.7 ± 2.3% was successfully fabricated by casting, heat treatment and hot extrusion. The effects of intermetallic compounds on microstructure and mechanical properties were deeply investigated. The results show that the studied alloy consists of coarse deformed α-Mg grains with (0001) basal texture, fine recrystallized β-Li grains with (002) texture and three Mg3RE phase variants, which are bulk Mg3RE phase with a size range of 10–30 µm, spot Mg3RE phase with a size range of 1–2 µm and spherical Mg3RE phase with a size range of 0.3–1 µm, respectively. The spherical Mg3RE phase has a strong dispersion strengthening effect, while the bulk Mg3RE phase acts as crack resources and deteriorates the ductility. A novel island-like β1R phase (FCC, a = 0.78 nm) is found for the first time in the Mg-Gd-Li based alloys. It has a coherent (1̅12)β1R//(101̅0)α interface at the broad facet and a semi-coherent (1̅11)β1R//(112̅0)α interface at the end facet. The β1R phase transforms from βH phase at the semi-coherent interface by atomic shear of RE and Mg atoms. The β1R phase provides a significant precipitation strengthening effect to the studied alloy, while the dissolution of β1R phase results in the age-softening phenomenon. The high-performance of the studied alloy is mainly attributed to the α/β duplex structure, three Mg3RE phase variants, and β1R phase.

The role of Ga in the microstructure, corrosion behavior and mechanical properties of as-extruded Mg–5Sn–xGa alloys

The effect of Ga element on microstructure, corrosion behavior and tensile mechanical properties of as-extruded Mg–5Sn–xGa (x = 0, 1, 2, 3, all in wt%) alloys was investigated using immersion test, electrochemical test and tensile test. The results show that the Mg2Sn and Mg5Ga2 particles are dynamically precipitated during extrusion process, and the volume fraction of Mg5Ga2 precipitates increases with increasing Ga content. The corrosion resistance of Mg–5Sn alloy in the immersion test is increased approximately by four times after adding 2 wt% Ga, due to the fact that the Ga element weakens the cathodic reaction, and more stable corrosion products are formed in the Ga-containing alloys in the inner corrosion layer. The tensile strength of investigated alloys is improved monotonously with increasing Ga content. The maximum elongation to fracture reaches up to 21.7% for Mg–5Sn–1Ga alloy due to the modified basal grain texture.

Influence of Sm addition on microstructural and mechanical properties of as-extruded Mg–9Li–5Al alloy

In this study, the influence of Sm addition on microstructural evolution and mechanical properties of as-extruded Mg–9Li–5Al (LA95) alloy was characterized by OM, SEM, TEM, XRD and EDS. The morphology results showed that adding Sm resulted in the formation of Al2Sm phase, and the grains of the LA95 alloy were markedly refined with the addition of Sm. Additionally, the dislocation pile-up around the Al2Sm particles were observed by high-resolution transmission electron microscopy. The as-extruded LA95-0.4Sm alloy with granular Al2Sm phase showed optimal ultimate tensile strength of 283 MPa, which was about 25% higher than that of the matrix alloy. The main factors influencing the strength of as-extruded LA95-xSm alloys were as follows: (i) grain refinement strengthening, the lattice mismatch calculation results showed that the average lattice mismatch of (111)Al2Sm//(0001)α-Mg was 12.5%, which indicated that the Al2Sm phase served as an effective heterogeneous nucleation substrate of the α-Mg phase to refine the α-Mg phase in LA95 alloys; (ii) second phase strengthening, the fine Al2Sm particles exerted positive effects on strengthening by effectively hindering the dislocation line movement, thereby forming the dislocation pile-up adjacent to the strengthening phase Al2Sm.

Effect of Al on microstructure and mechanical properties of as-extruded Mg–1Mn alloy sheet

The effect of Al addition on microstructure and mechanical properties of hot extruded Mg–1Mn alloy sheet was investigated. The results revealed that the dynamic recrystallization was promoted by increasing Al content. The ultimate tensile strength and yield strength of the alloy increased with the increase of Al content. The Mg–9Al–1Mn alloy exhibited the highest strength, with tensile strength of 308 MPa, 307 MPa, 319 MPa, yield strength of 199 MPa, 207 MPa, 220 MPa and the elongation of 20.9%, 20.1%, 19.2% in 0°, 45°, 90°, respectively. The high strength was mainly attributed to the formation of fine dynamically recrystallized grains and large amounts of the second phase. The strengthening mechanism of the alloys was explained.

Effects of Ca addition on the microstructures and mechanical properties of as-extruded Mg–Bi alloys

Abstract The microstructure and mechanical properties of as-extruded Mg–1.3Bi–xCa (x = 0, 0.4, 0.9, and 1.3 wt%) were investigated. All samples exhibit full dynamic recrystallization; the mean grain size first increases slightly and then decreases significantly. Additionally, both Mg2Bi2Ca and Mg2Ca phases are formed with increasing Ca content. In particular, the dynamic precipitation of nanoscale Mg2Ca is enhanced remarkably. The typical fiber basal texture in Ca-free binary alloy transformed into a rare-earth texture with the components of [ 1 ¯ 2 1 ¯ l] and [01 1 ¯ l]//extrusion direction in Ca-bearing ternary alloys. In addition, the tensile elongation increases significantly with a trace amount of Ca addition (0.4 wt%), but an overdose of Ca addition (1.3 wt%) results in the formation of a large number of microscale Mg2Bi2Ca phases. The Mg-1.3Bi-0.9Ca alloy demonstrates the optimal balance of ductility and strength with an excellent elongation of 40% and yield strength of 158 MPa, owing to texture modification and grain refinement. This study may provide insights into the development of high-ductility, low-cost Mg–Bi-based alloys using microstructure tuning and texture modification.

Development of high strength and ductility in Mg–2Zn extruded alloy by high content Mn-alloying

Mg–Zn–Mn alloys have drawing crucial attention because of the high strength, high ductility and excellent age harden ability. In the current work, we have systematically investigated the influence of Mn on the microstructure evolution and mechanical properties of as-extruded Mg–2Zn–Mn alloy. Results revealed that the mechanical properties that containing tensile and compressive strengths remarkably increased with high Mn content (2 wt%) addition. The dynamic recrystallized grains of Mg–2Zn alloy were significantly refined from 20 μm to 2 μm because of a mass of fine Mn precipitates effectively blocked newborn grain growth during extrusion process. The enhanced strengths were mainly ascribed to the high volume fraction of fine grains and the numerous fine precipitates. The strengthening mechanism and strain hardening behaviors of the alloys were also discussed.

Effects of secondary phases on texture and mechanical properties of as-extruded Mg–Zn–Er alloys

Abstract The effects of kinds of secondary phases on texture and mechanical properties of Mg–Zn–Er alloys were investigated. The results suggest that the I-phase has a great effect on modification of the texture via the discontinuous dynamic recrystallization mechanism (DDRX), which tends to form well-developed equiaxed recrystallized grains. Meanwhile, the W-phase plays an important role in refining the grain size via continuous dynamic recrystallization (CDRX), companied with a higher maximum texture intensity. Thus, the Mg–6Zn–1Er alloy containing I-phase shows a performance of higher elongation of 20.4%. The Mg–2Zn–2Er alloy including W-phase displays a better tensile strength, and the yield strength (YS) is about 247 MPa.

Effect of Zr on the microstructures and mechanical properties of as-extruded Mg–2.3Zn–0.18Y–xZr alloys

The microstructures and mechanical properties of as-extruded Mg–2.3Zn–0.18Y–[Formula: see text]Zr ([Formula: see text] = 0.03, 0.06 and 0.13 at.%) alloys and aged Mg–2.3Zn–0.18Y–0.13Zr alloy were studied. The results revealed that the microstructures of as-extruded Mg–2.3Zn–0.18Y–[Formula: see text]Zr alloys are typical bimodal structures. The coarse [Formula: see text]-Mg grains are surrounded by fine dynamically recrystallized [Formula: see text]-Mg grains. The average size of [Formula: see text]-Mg grains decreases with increasing Zr content. Moreover, the addition of Zr (at.%) can improve the mechanical properties of alloy. The as-extruded Mg–2.3Zn–0.18Y–0.13Zr alloy has the best mechanical properties with ultimate tensile strength (UTS) and yield strength (YS) of 346 MPa and 292 MPa, respectively, and an elongation of 26.7%, which can be attributed to the grain refining effect and precipitate strengthening. The UTS and elongation of Mg–2.3Zn–0.18Y–0.13Zr alloy changed slightly after aging treatment, but the YS increases remarkably, with the maximum increase of 30 MPa. The fracture surfaces of all alloys consist of many tearing ridges and dimples.

Microstructure, texture and mechanical properties of Mg–Zn–Er alloys containing I-phase and W-phase simultaneously

The microstructure, texture and mechanical properties of Mg–9Zn–xEr (x = 3, 4.5 and 6 wt.%) alloys have been investigated. It was found that the main phase compositions of the present Mg–9Zn–xEr alloys were composed of I-phase and W-phase as well as the α-Mg solid solution. The volume fraction of the secondary phases, especially for the W-phase which increased as the content of the Er element increased. The increment in the content of the W-phase led to unexpected results in the associated texture and mechanical properties. The texture was not weakened as the volume fraction of the secondary phase increased compared with those of Mg–Zn–Er alloys containing I-phase or W-phase exclusively, respectively. Whereas, the mechanical properties of as-extruded Mg–9Zn–xEr alloys displayed a tendency to increase with the content of Er increasing. The best mechanical properties had been observed in the Mg–9Zn–6Er alloy after hot extrusion at 300 °C, and the values of the ultimate tensile strength and the elongation were 338 (±5.2) MPa and 13.8 (±1.0)%, respectively. The hot extrusion temperature did not play an important role in influencing mechanical properties.

Microstructures and mechanical properties of as-extruded Mg–5Sn–1Zn–xAl (x=1, 3 and 5) alloys

As-extruded Mg–5Sn–1Zn–xAl alloys (x=1, 3, and 5) were fabricated by hot extrusion. The experimental results revealed that the yield strength of alloys initially decreased and then increased with the increase of Al content. These changes were mainly attributed to the difference in crystallographic texture and volume fractions of second phases. The ultimate tensile strength, yield strength, and elongation of the alloys were greater than 310MPa, 227MPa, and 11%, respectively. The strain hardening ability of the alloys was also discussed.

Microstructure, texture and mechanical properties of as-extruded Mg–Zn–Er alloys containing W-phase

In the present work, the microstructure, texture and mechanical properties of as-extruded Mg–xZn–xEr (x=2, 4 and 6) alloys were investigated. The results showed that the W-phase in the as-cast alloys was destroyed during hot extrusion process. The distribution of the W-phase is more uniform when the extrusion temperature is 400°C, and the texture has also been a certain degree of weakening. With increase in the volume fraction of the primary W-phase, the particle-stimulated nucleation (PSN) of recrystallization was activated. It was suggested that the recrystallization via PSN should lead to weak texture. Good matching between strength and elongation is achieved in the Mg–6Zn–6Er alloy extruded at 400°C, of which the ultimate tensile strength (σb) and the yield tensile strength (σ0.2) were 328 (±2.5)MPa and 283 (±2.2)MPa, respectively, companying with an elongation of 19.7% (±1.2).

Influence of biocorrosion on microstructure and mechanical properties of deformed Mg–Y–Er–Zn biomaterial containing 18R-LPSO phase

The microstructure and mechanical properties of as-extruded Mg–8Y–1Er–2Zn (wt%) alloy containing long period stacking ordered (LPSO) phase are comparatively investigated before and after corrosion in a simulated body fluid (SBF) at 37°C. The as-extruded alloy consists of a long strip-like 18R-LPSO phase and some fine lamellae grains formed by primary recrystallization during the extrusion process. The hydrogen evolution volume per day fluctuates between 0.21 and 0.32ml/cm2 in the immersion test for 240h, and the corresponding corrosion rate is calculated as 0.568mm/y. The corrosion product is determined as Mg(OH)2, whilst a Ca(H2PO4)2 compound is also observed on the surface of the samples. The corrosion site preferentially occurs at the interface between LPSO phase and Mg matrix. Before immersing, the tensile yield strength (TYS), ultimate tensile strength (UTS) and elongation of the alloy are 275MPa, 359MPa, and 19%, respectively. More attractively, these mechanical properties can be maintained even after immersing in SBF for 240h (TYS, UTS and elongation are 216MPa, 286MPa and 6.8%, respectively) because of the existence of high anti-corrosion LPSO phase.

Microstructure, texture and mechanical properties of as-extruded Mg–Zn–Er alloys

In the present work, the microstructure, texture and mechanical properties of the as-extruded Mg–xZn–yEr (x=3, 6 and 9; y=0.5, 1 and 1.5; x/y=6) alloys were investigated. The results showed that the I-phase in the as-cast alloys was destroyed and lots of nano-scale quasicrystalline particles were precipitated within the matrix during hot extrusion process. With the increase in the volume fraction of the primary I-phase, the particle-stimulated nucleation (PSN) of recrystallization was activated. It was suggested that the recrystallization via PSN should lead to the nucleation of new grains with a high orientation mismatch to the parent grains, making the texture gradually weaken. Significant strengthening is achieved in the Mg–9Zn–1.5Er alloy, of which the ultimate tensile strength (σb) and the yield tensile strength (σ0.2) were 319MPa and 192MPa, respectively, with an elongation of 22.3%.

Low temperature mechanical properties of as-extruded Mg–10Gd–3Y–0.5Zr magnesium alloy

Influence of multi-cycle cryogenic treatment and tensile temperature on microstructure, mechanical properties and fracture mechanism of as-extruded Mg–10Gd–3Y–0.5Zr magnesium alloy was investigated. The results show that there have no significant changes in tensile properties of the tested alloy after 10 d in liquid nitrogen immersion or 10 cycles of high-low temperature treatment at all test temperatures. The room temperature ultimate tensile strength increases from 398 MPa to 417 MPa after 20 cycles of high-low temperature treatments. Compared with the room temperature, the tested alloys exhibit higher tensile properties at low temperatures. At −196 °C, the yield strength and ultimate tensile strength of the as-extruded-T5 Mg–10Gd–3Y–0.5Zr alloy are 349 MPa and 506 MPa, respectively, increasing by about 18% and 27%, respectively. The transgranular cleavage fracture mechanism is observed at room temperature, while at low temperatures both ductile fracture and cleavage fracture behaviors coexist.

Influence of the morphology of long-period stacking ordered phase on the mechanical properties of as-extruded Mg–5Zn–5Y–0.6Zr magnesium alloy

In this study, the influence of the different microstructure and morphology of long-period stacking ordered (LPSO) X-phase (Mg12YZn) on the mechanical properties of as-extruded Mg–5Zn–5Y–0.6Zr (wt.%, nominal chemical composition) alloys, tailored by different extrusion parameters, were investigated using tensile tests, optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectrometer, X-ray diffractometer and transmission electron microscopy. Under an extrusion ratio of 11 and extrusion temperature set at 450°C, the discontinuous network morphology of LPSO phases along the grain boundaries created an alloy that had good ductility, characterised by 20.3% elongation. Under an extrusion ratio of 89 and extrusion temperature set at 500°C, the dispersive block-shaped LPSO phases and refined grains made the alloy to obtain an ultimate tensile strength of 412MPa, tensile yield strengths of 380MPa and elongation of 11.8%. Therefore, while the existence of LPSO phases contributes to the alloy strengthening, the morphology regulation and control of LPSO phases can further enhance their strength.

The effect of nanoquasicrystals on mechanical properties of as-extruded Mg–Zn–Gd alloy

The Mg-3.5Zn-0.6Gd (at. %) alloy was prepared and homogenized at 673K for 8h, and then extruded at 523K with an extrusion ratio of 9:1. The microstructure and mechanical properties of the extruded alloy have been investigated. Icosahedral quasicrystalline phase (I-phase) existed in extruded Mg–Zn–Gd-based alloys in two morphologies: (1) micron-scale I-phase formed in the solidification, (2) nano-scale ellipsoid-shape I-phase particles precipitated in the extrusion process. A definite orientation relationship and good atomic match between I-phase and α-Mg matrix were directly observed by conventional and high-resolution transmission electron microscopy (HRTEM), which contribute to the high tensile strength of 308MPa and the large plasticity of 16.4%.