Al8Mn5 Phase Research Articles

Microstructural characterization and creep behavior of dispersion strengthened MRI230D magnesium alloy

The microstructural changes following the dispersion of SiC nanoparticles (SiCnp) and its subsequent significance on the creep response of MRI230D alloy are examined. Nanocomposites (NCs) of MRI230D alloy are fabricated with a dispersion of 1.0SiCnp (NC1SiC) and 2.0SiCnp (NC2SiC) (wt.%) using squeeze-casting. The primary Mg (α-Mg), lamellar C36 (Mg,Al)2Ca, as well as blocky Al8Mn5 phases, are observed in the MRI230D alloy and NCs. Additionally, SiC phase is detected in NCs. The additions of SiCnp refine the grains of the NCs. The fraction of C36 increases with an increase in SiCnp in MRI230D alloy. The alloy and NCs are exposed to impression creep tests under 450–500 MPa stress and 448–498 K temperature. The NCs exhibit better resistance to creep over MRI230D alloy, and NC2SiC is the most creep-resistant. The strengthening from the increased fraction of C36, along with Orowan strengthening from SiCnp dispersion in the α-Mg matrix, give rise to improved creep strength of the NCs than the alloy. The creep in MRI230D alloy and NCs progressed by dislocation-climb with pipe diffusion.

Microstructural refinement and mechanical properties improvement of Mg–Al–Mn–Zn–Ca alloy processed by rotary swaging at room temperature

Mg-4.1Al-0.6Mn-0.5Zn-0.4Ca alloy with high strength was prepared through hot extrusion at 330 °C followed by room temperature rotary swaging. The changes of microstructure and mechanical behaviors of extruded and swaged alloys after undergoing different rotary waging passes were investigated. The results reveal significant microstructural refinement, fragmentation of the Al8Mn5 phases, and precipitation of the Al2Ca phases after rotary swaging. With the increase of rotary swaging passes, a noticeable rise in the fraction of LAGBs and a more uniform distribution and refinement of second phases occurred. The texture with <10–10> parallel to processing direction was formed after rotary swaging. The rotary swaging largely improves the alloy's strength, with the ultimate tensile strength and yield strength increasing from 298 MPa to 198 MPa for the as-extruded alloy to 372 MPa and 359 MPa for the as-swaged alloy after 13 passes, respectively. The improvement of mechanical properties is a result of grain boundary strengthening, dislocation strengthening, and the strengthening of second phases. This result may provide valuable insights and guidance in the design of high-strength magnesium alloys as well as their plastic processing methods.

Microstructure evolution and assessment of creep behaviour of SiC nanoparticles dispersed squeeze-cast Mg-5.0Al-2.0Ca-0.3Mn alloy

The microstructural modification and creep behaviour of Mg-5.0Al-2.0Ca-0.3Mn (AXM520) alloy with SiC nanoparticles (SiCnp) dispersion have been investigated. The concentrations of the SiCnp are varied from 0.5 to 3.0 (wt.%), and the squeeze-cast nanocomposites (NCs) are abbreviated as NC0·5SiC, NC1·0SiC, NC2·0SiC and NC3·0SiC. The microstructures of the AXM520 alloy and NCs consist of a primary solid solution (α-Mg), a eutectic of α-Mg and (Mg,Al)2Ca (C36), and an Al8Mn5 phase. Additionally, the SiC phase is also present in the NCs. The continuous network of the C36 phase in the NCs is fragmented and becomes discontinuous with the increase in the fraction of the SiCnp. All the NCs revealed improved creep performance compared to the AXM520 alloy. The creep rate of the NCs decreases with the increase in the SiCnp content. The NC2·0SiC exhibited an improvement in creep resistance by 73.2 % compared to the alloy. However, the creep resistance deteriorated since the amount of the nanoparticles was further increased in the NC3·0SiC, leading to agglomeration. The stress exponents vary from 5.0 to 6.7, and activation energies vary from 89.8 to 101.8 kJ/mol, implying that the creep in the materials is controlled by the climb of dislocation assisted by the pipe diffusion. The pile-ups of dislocations took place around the C36 phase and near the SiCnp. The additional strengthening owing to the presence of the SiCnp in the NCs was responsible for their improved creep performance compared to the AXM520 alloy.

A new heterogeneous nucleation mechanism of AM30 alloy refined by carbon inoculation

The AM30 alloy experiences remarkable grain refinement through carbon inoculation, resulting in a significant reduction of grain size from 623±21μm to 82 ± 2 μm. To delve into the influence of Mn on carbon inoculation in the presence of Ca, advanced techniques such as EDS, FIB, and TEM were utilized. This study reports the initial discovery of a unique duplex-phase particle characterized by an amorphous carbon layer coating on the Al8Mn5 phase. Notably, the amorphous layer exhibits a thickness of approximately 100 nm. These distinctive duplex-phase particles are hypothesized to serve as effective nuclei for Mg grains. Supported by epitaxial growth theory and experimental data, these particles exhibit remarkable nucleation efficiency.

SiC nanoparticles additions to squeeze-cast Mg-5.0Al-2.0Ca-0.3Mn alloy: An evaluation of microstructure and mechanical properties

The influences of the SiC nanoparticles (SiCnp) content on the microstructural modification and mechanical properties of the squeeze-cast Mg-5.0Al-2.0Ca-0.3Mn (AXM520) alloy have been investigated. The concentrations of the SiCnp are varied from 0.5 to 3.0 (wt%), and the nanocomposites (NCs) are abbreviated as NC0.5SiC, NC1.0SiC, NC2.0SiC and NC3.0SiC. The as-cast microstructures of the AXM520 alloy and NCs consist of an α-Mg phase, a eutectic of α-Mg and (Mg,Al)2Ca (C36), and an Al8Mn5 phase. Additionally, the SiC phase is also present in the NCs. The continuous network of the C36 phase is fragmented and becomes discontinuous as the content of the SiCnp increases in the NCs. All the NCs exhibit superior tensile and compressive properties than the AXM520 alloy. The NC2.0SiC exhibits the best tensile properties among the NCs employed. The YS of the NCs improves with the increase in the SiCnp content up to 3.0 (wt%). The UTS and %El of the NCs increase up to 2.0SiCnp (wt%), and beyond that, the same declines owing to the agglomeration of the nanoparticles. The discontinuous network of the C36 phase in the NCs inhibits crack propagation, leading to their improved %El. All the NCs exhibit higher strain-hardening exponent (n) and strain-hardening rate (SHR) compared to the AXM520 alloy. The superior ‘n’ and SHR exhibited by the NCs were attributed to the grain refinement and dislocations generation. The strengthening from CTE mismatch contributes the most to the overall strengthening of the NCs. The ‘Zhang and Chen’ model is modified by introducing an agglomeration factor, and the predicted YS of the NCs matches pretty well with the experimentally obtained values.

Effect of Al on the Microstructure and Mechanical Properties of Mg-6Zn Alloy

In this work, the effect of trace Al on the microstructure and mechanical properties of Mg-6Zn alloy was studied. The results show that the as-cast ZM60 alloy consists of α-Mg phase and Mg51Zn20 phase. After the addition of Al, fine Al8Mn5 phase increases in the microstructure of the experimental alloy, and the number of the second phase increases. Dynamic recrystallization occurred in all the experimental alloys during extrusion deformation, the grain size of Al alloy is significantly smaller than that of ZM60 alloy, and the average grain size of ZAM610 alloy is the smallest, which is 5.6µm. ZAM610 alloy has the best mechanical properties, with tensile strength, yield strength, elongation after fracture, U-notch impact work and non-notch impact work of 302.7MPa, 216MPa, 19.7%, 10.0 J/cm2 and 56.0 J/cm2, respectively. The fracture of the impact sample shows that there are many tearing edges in the ZM60 alloy, which shows the characteristics of quasi-cleavage fracture. The ZAM600 and ZAM610 alloys have a large number of dimples, which are characterized by dimple fracture. The improved properties of magnesium alloys after microalloying can be attributed to the formation of fine Al8Mn5 phase, which has good Zener blocking effect, refines the dynamic recrystallized grains, and improves the strength and impact toughness of the alloy.

Low-cost high-strength Mg–7Zn-xAl-0.3Mn (x=1, 3, 5) cast magnesium alloys via grain boundary strengthening and precipitation strengthening

Obtaining a highly synergistic strength and elongation in cast magnesium (Mg) alloys at low cost is a chronic problem. A series of low-cost and high strength cast Mg–7Zn-xAl-0.3Mn (x = 1, 3, 5) alloys (labeled as ZAM710, ZAM730, and ZAM750 alloys, respectively) were designed based on the phase diagram simulation and prepared successfully by electric resistance furnace. The present results showed that the as-cast ZAM710 alloy was composed of α-Mg, MgZn, AlMn, and Al8Mn5 phases. The MgZn phase disappeared and the Mg32(Al, Zn)49 phase formed as the Al content increased to more than 3 wt%. In addition, with the increase of Al content, the volume fraction of the second phase increased and the grain was refined. The microstructures and mechanical properties of these alloys were improved after heat treatment. Among them, the transmission electron microscopy analysis showed that there were a large number of nanometer precipitation strengthening phases in the aged ZAM750 alloy. One was a rod-shaped Mg4Zn7 phase and the other was a disk-shaped MgZn2 phase. The comprehensive mechanical properties of the ZAM750 alloy were most outstanding, and the tensile strength, yield strength, and elongation were 309.4 MPa, 202.0 MPa, and 6.1%, respectively. The strengthening mechanism of the ZAM750 alloy mainly included grain boundary strengthening and precipitation strengthening, and the contribution values to the yield strength of the ZAM750 alloy were 95.8 MPa and 75.7 MPa, respectively. This work can provide some guidance and new design ideas for the development of low-cost and high-strength cast Mg alloys.

Tailoring the structure, mechanical, electronic, and thermodynamic properties of Al8Mn5 by doping Ti atom with different atomic site configurations

To solve the problem of the influence of Ti particles on Al8Mn5 phases is difficult to observe from the experiments, the effects of Al8Mn5 doped with Ti atom at different Wyckoff sites on its thermodynamic properties, mechanical properties, and electronic structural characteristics were systemically studied by first-principles calculations in this work. It was found that the doping of Ti can enhance the thermodynamic, dynamic, and mechanical stability, change the elastic anisotropy in different directions, and decrease the ductility of Al8Mn5. The calculated mechanical results showed that the bulk modulus decreased, while the Young's modulus (E), hardness (HV), and shear modulus improved for the Ti-doped Al8Mn5 phases. The Al–Ti5 phase in Ti doping Al sites and the Mn–Ti3 phase in Ti doping Mn sites have the largest E with the values of 234.59 and 233.25 GPa, respectively. Additionally, the Al–Ti5 and the Mn–Ti3 phases have the highest HV of 16.24 and 16.06 GPa in Chen's model, and 14.31 and 14.48 GPa in Tian's model, respectively. The electronic structures and chemical bonding characteristic information elaborated that the improvement in mechanical properties is due to the improvement in Al–Mn and Al–Al bond strength.

STRUCTURE, MECHANICAL PROPERTIES, AND OXIDATION RESISTANCE OF MN-RICH FE-MN-AL ALLOYS

In this study, Mn-rich Fe-Mn-Al alloys with different Al content (Al = 0, 3, and 5 % by weight) were fabricated from ferromanganese lumps using a conventional powder metallurgy technique. The samples were compacted in 1 cm steel dies using a load of 8 tons and then sintered at 1100 °C for 2 h in a tubular furnace under a vacuum condition of around 0.5 mbar. To evaluate the effect of Al addition to Fe-Mn-Al alloy, the Archimedes principle and Vickers hardness were applied to estimate the density and hardness of the compact alloys. Moreover, the high-temperature oxidation resistance of the alloy was evaluated at 800 °C for 8 cycles. The structure of the alloy before and after oxidation was studied by means of X-Ray Diffractometer and SEM-EDS. The XRD analysis results show that the FeMn-0Al alloy is mainly composed Fe3Mn7 phase, the presence of FeAl phase at 3 wt% Al, and Al8Mn5 phase at 5 wt% Al. The density and hardness of Fe-Mn-Al alloys decreased with the increased Al content. Fe-Mn-Al alloy without Al addition exhibits poor oxidation resistance since the first cycle of the test. The results of microstructural analysis showed that although the alloy with the addition of 3 wt% Al showed less mass gain after being exposed for 8 cycles at 800 °C, the Fe-Mn-Al alloy with 5 wt% tended to be more resistant to oxidation and had no cracking defects. The structure of the oxide formed on the surface of the alloy is composed of two layers (ie; outer and inner layer) which are affected by each alloy composition.

Influence of microstructures on mechanical properties of the Csf/Mg composite fabricated by liquid-solid extrusion following vacuum pressure infiltration

The short carbon fiber reinforced magnesium matrix composite (Csf/Mg) with a fiber volume fraction of up to 20 % was fabricated by liquid-solid extrusion following vacuum pressure infiltration (LSEVI) method. The effects of pressure (20, 30, 40, and 50 MPa) and temperature differences (515.9–590.7 °C) on the densification and precipitated phases of the composite have been fully investigated. Meanwhile, the tensile property and hardness were tested at different regions including the interface, the top, middle, and bottom regions of the prepared composite billets. The results show that an appropriate holding pressure can prevent shrinkage defects and decrease fiber aggregations. The hard and brittle Al8Mn5 phase was found near fibers and in the interfacial zone between the composite and the magnesium alloy. The phase and fibers together refine α-Mg grains and enhance the mechanical properties of the composite. It has also been found that both the ultimate tensile strength (UTS) and the hardness peak in the middle region. Compared with the magnesium alloy matrix, the UTS and the hardness of the composite have been increased by 55.5 % (∼213 MPa) and 97 % (∼98 HV), respectively. Based on the present studies, the intrinsic relationship among the process parameters, microstructures, and performances of the Csf/Mg composite has been clarified.

Elucidating dynamic precipitation and yield strength of rolled Mg–Al–Ca–Mn alloy

Although the precipitation and recrystallization of Mg–Al–Ca–Mn based alloys have been well investigated individually, there is still a lack of a detailed investigation on the effect of the Al-rich clusters, Mn-rich precipitates and/or Ca-rich Laves phases formed from dynamic precipitation during rolling on the grain size and texture as well as yield strength. Here, we have investigated the effect of Mn (1 wt. %) on the dynamic precipitation and yield strength of rolled Mg–3Al–1Ca alloy after rolling up to 1 and 6 passes (at 350 °C and 300 °C). It was found that an effective grain refinement can be obtained due to the fact that the dynamic precipitation enhances dynamic recrystallization by particle stimulated nucleation (PSN) mechanism. No significant texture change was obtained although the dynamic precipitation of Mn-rich particles due to the addition of 1 wt. % Mn results in a change from an RD-split texture to a strong basal texture. Three different Mn-rich phases ((i) large primary Al8Mn5 phase, (ii) the long plated-shaped Al8Mn5 phase, and (iii) nanoscale Al8Mn5 phase), C15 Laves phase (Al2Ca) and Al-rich clusters (G.P. zone), were observed, while no plate-shaped Al–Ca precipitate was observed on the basal plane of α-Mg matrix, indicating a competition among the formation of Al-rich clusters, plate-like Al–Ca precipitates, Ca-rich Laves phase, and Mn–rich phase within α-Mg matrix. Dispersion strengthening by the Ca-rich Laves phase, Mn–rich phase and Al-rich clusters is proposed to be attributed to the significant improvement of yield strength. This investigation highlights the importance of elucidating the effect of the dynamic precipitation on yield strength of rolled Mg–3Al–1Ca–1Mn alloys and provides helpful hints to further optimize the deformation and mechanical properties of Mg–Al–Ca–Mn based alloys.

Transformation of Laves phases and its effect on the mechanical properties of TIG welded Mg-Al-Ca-Mn alloys

The effects of Al content and Ca/Al mass ratio on the microstructure and mechanical properties of tungsten inert gas (TIG) welded Mg-2Ca-xAl-0.5Mn (x=0, 1, 5) alloy joints were studied in present work. Results showed that increasing Al content was effective in reducing the dendrite spacing at the fusion zone (FZ) edge. The Laves phases in the FZ and the heat-affected zone (HAZ) can be changed from Mg2Ca to (Mg, Al)2Ca with the decrease of Ca/Al ratio, and the (Mg, Al)2Ca could be further transformed to Al2Ca under welding thermal cycle. Furthermore, dynamic dissolution and precipitation of Laves phases and Al8Mn5 phases occurred in the HAZ, resulting in a gradient microstructure and hardness peak in this area. The tensile properties of the joints were significantly improved with the increase of Al content, which was mainly due to the modification of Laves phases.

Investigation on microstructure and mechanical properties of hot-rolled AZ31 Mg alloy with various cryogenic treatments

AZ31 Mg alloy sheet, prepared by a novel process combining hot rolling and various cryogenic treatments, has been investigated on its microstructure and mechanical properties. The results show that twins and the Al8Mn5 phase were introduced in the sample with rapid cooling and rapid heating and slow heating and slow cooling, which can significantly impede the movement of dislocations, while twins also can effectively coordinate deformation. Compared to the conventional hot rolling sample, the average grain size and texture strength of the cryogenic treatment samples were refined and increased by ∼24% and∼50%, respectively. The dislocation density of the coarse-grained region in the sample with slow heating and slow cooling is low, and the prismatic <a> and pyramid <c+a> slips were activated, which can improve the ductility of the alloy. In comparison to conventional hot rolling, the ultimate tensile strength and elongation of AZ31 Mg alloy after rapid cooling and rapid heating were increased by ∼15% and ∼37%, respectively, while the elongation after slow heating and slow cooling increased by ∼71%. The improvement of the mechanical properties of Mg alloy with cryogenic treatment is attributed to the synergistic effect of the refined grain, twins, residual dislocations, precipitates, texture and non-basal slip.

Effect of micro-alloyed Ce on the microstructure evolution and mechanical properties of rolled Mg–0.6Al–0.5Mn–0.2Ca alloy sheets

In this study, the effect of minor Ce addition (0, 0.1, and, 0.3 wt.%) on the microstructure evolution and mechanical properties of rolled Mg–0.6Al–0.5Mn–0.2Ca (AMX100) alloy sheets is systematically investigated under different annealing processes. With 0.1 wt.% Ce addition, partial Al8Mn5 phases turn into Al8Mn4Ce. With 0.3 wt.% Ce addition, the number of the Al8Mn4Ce further increases and the Al–Ce phases are observed. The single-stage annealed alloys exhibit similar uniform fine-grained structures (∼6 μm) regardless of the Ce content, while the grain sizes of the two-stage annealed alloys increase obviously (∼10.9–11.9 μm). Especially, the abnormal grain growth occurs in the two-stage annealed AMX100-0.3Ce alloy. After the aging treatment, the yield strength (YS) of the two-stage annealed alloys is increased by ∼25–45 MPa, which is greatly higher than that of the single-stage annealed alloys (∼1–8 MPa). Note that the two-stage annealed AMX100–0.1Ce alloy displays a significant age-hardening response with the ultimate tensile strength (UTS) of ∼272 MPa and the elongation to failure (EF) of ∼14%, which is attributed to the formation of Al and Ca enriched Guinier-Preston (G.P.) zones. This work sheds light on the design and fabrication of low-cost dilute magnesium alloys with admirable age-hardening ability.

Corrosion resistance of Mg-Al-LDH steam coating on AZ80 Mg alloy: Effects of citric acid pretreatment and intermetallic compounds

In this study, the effects of intermetallic compounds (Mg17Al12 and Al8Mn5) on the Mg-Al layered double hydroxide (LDH) formation mechanism and corrosion behavior of an in-situ LDH/Mg(OH)2 steam coatings on AZ80 Mg alloy were investigated. Citric acid (CA) was used to activate the alloy surface during the pretreatment process. The alloy was first pretreated with CA and then subjected to a hydrothermal process using ultrapure water to produce Mg-Al-LDH/Mg(OH)2 steam coating. The effect of different time of acid pretreatment on the activation of the intermetallic compounds was investigated. The microstructure and elemental composition of the obtained coatings were analyzed using FE-SEM, EDS, XRD and FT-IR. The corrosion resistance of the coated samples was evaluated using different techniques, i.e., potentiodynamic polarization (PDP), electrochemical impedance spectrum (EIS) and hydrogen evolution test. The results indicated that the CA pretreatment significantly influenced the activity of the alloy surface by exposing the intermetallic compounds. The surface area fraction of Mg17Al12 and Al8Mn5 phases on the surface of the alloy was significantly higher after the CA pretreatment, and thus promoted the growth of the subsequent Mg-Al-LDH coatings. The CA pretreatment for 30 s resulted in a denser and thicker LDH coating. Increase in the CA pretreatment time significantly led to the improvement in corrosion resistance of the coated AZ80 alloy. The corrosion current density of the coated alloy was lower by three orders of magnitude as compared to the uncoated alloy.

Effect of Al addition on microstructure and mechanical properties of Mg−Zn−Sn−Mn alloy

The microstructure and properties of the as-cast, as-homogenized and as-extruded Mg−6Zn−4Sn−1Mn (ZTM641) alloy with various Al contents (0, 0.5, 1, 2, 3 and 4 wt.%) were investigated by OM, XRD, DSC, SEM, TEM and uniaxial tensile tests. The results show that when the Al content is not higher than 0.5%, the alloys are mainly composed of α-Mg, Mg2Sn, Al8Mn5 and Mg7Zn3 phases. When the Al content is higher than 0.5%, the alloys mainly consist of α-Mg, Mg2Sn, MgZn, Mg32(Al,Zn)49, Al2Mg5Zn2, Al11Mn4 and Al8Mn5 phases. A small amount of Al (≤1%) can increase the proportion of fine dynamic recrystallized (DRXed) grains during hot-extrusion process. The room- temperature tensile test results show that the ZTM641−1Al alloy has the best comprehensive mechanical properties, in which the ultimate tensile strength is 332 MPa, yield strength is 221 MPa and the elongation is 15%. Elevated- temperature tensile test results at 150 and 200 °C show that ZTM641−2Al alloy has the best comprehensive mechanical properties.

In Situ Observation of the Degradation Behavior and the Systematic Investigation of Corrosion Mechanism in AZ31 Alloy

The degradation behaviors of as‐received and as‐solutionized AZ31 alloys in Hanks’ solution are in situ studied by a 3D digital optical microscope. The initiation and extension processes of corrosion are investigated. Long‐time immersion and electrochemical tests are applied to investigate the corrosion mechanism systematically. The corrosion attacks of as‐received and as‐solutionized AZ31 alloy both start from the grain boundaries (with and without the Al8Mn5 phase) while show no preferential propagation, and the scratches also can act as the corrosion starting positions. The Al8Mn5 phase does not show an obvious accelerated effect on the Mg matrix's corrosion, and it also suffers corrosion. Solid solution treatment can enhance the corrosion resistance of AZ31 alloy is primarily due to the reduced dislocation density. Degradation products on as‐received AZ31 alloy are studied, the Al, Zn, and Mn elements degrade as Al2O3, ZnO, and MnO, respectively.

Microstructural evolution and its implications on the mechanical properties during age hardening in Mg-1Al-0.28Ca-0.13Mn-0.05Si alloy

A cast Mg-1Al-0.28Ca-0.13Mn-0.5Si (wt%) alloy has been subjected to solution-annealing at 723 K followed by aging treatment at 473 K. The specimens aged for 15 min, 60 min, and 900 min were considered as the under-aged, peak-aged, and over-aged specimens based on the microhardness variations. In comparison to the solution-annealed condition, the peak-aged specimen exhibits excellent strengthening i.e. ~87% increase in the yield strength and ~37% rise in the ultimate tensile strength, at the expense of ~41% decrease in the ductility. The evolution of nano-sized Al-Mn particles and coarse Ca-rich phases takes place with the aging of the alloy specimens. The Al-Mn phase has been identified as the Al8Mn5 phase with the aid of X-ray diffraction, scanning transmission electron microscopy, high-resolution transmission electron microscopy, and 3D atom probe tomography. The changes in the size, fraction, and nature of precipitate-dislocation interactions depending on the coherency of the nano-sized Al8Mn5 precipitates, are accountable for strengthening in the different aging stages of the developed alloy. Precipitate-dislocation interactions involving precipitate-shearing mechanism leads to the excellent strengthening in the peak-aged specimen. Contrarily, the evolution of the crack-initiating coarse (Mg,Al)2Ca phase leads to the loss of ductility in the peak-aged and over-aged specimens.

Effect of Modification on Microstructure and Properties of AZ91 Magnesium Alloy

Refinement of α-Mg solid solution grains has a significant influence on the improvement of mechanical properties of cast magnesium alloys. In the article, the effects of three modifiers on microstructure and properties of AZ91 magnesium alloy casted to a sand mould were described. Overheating, hexachloroethane and wax-CaF2-carbon powder were applied. The research procedure comprised microstructure analysis by means of light microscopy, scanning electron microscopy and quantitative analysis with AnalySIS Pro® software and mechanical properties’ investigation. The microstructure of AZ91 alloy in the as-cast condition consists of α-Mg solid solution with precipitates of Mg17Al12, Mg2Si and Al8Mn5 phases. It was reported that all applied modifiers cause refinement of α-Mg solid solution grains and a decrease of the volume fraction of α-Mg+Mg17Al12 compound discontinuous precipitates. The best results were obtained in the case of wax-CaF2-carbon powder.

Microstructure and mechanical properties of AZ91 Mg alloy fabricated by cold metal transfer additive manufacturing

Based on the cold metal transfer (CMT) technique, AZ91 thick-walled component was fabricated by weaving wire and arc additive manufacturing (WAAM). The results showed that the deposited sample consisted of equiaxed grains with different sizes, and the sample was mainly composed of α-Mg, β-Mg17Al12 and Al8Mn5 phases. The anisotropy of the ultimate tensile strength between the transverse and longitudinal tensile samples was 2.0%, and the fracture surfaces exhibited typical ductile fracture characteristics. The component fabricated by the CMT-based WAAM system has better performance than the traditional cast alloy.