This work reveals a synergistic composition strategy for enhancing the strength-ductility balance of Al-Zn-Mg-Cu alloys by coupling Zn/Mg ratio optimization with Y microalloying. We demonstrate that increasing the Zn/Mg ratio (2.91 to 4.09) in Y-containing alloys refines the as-cast structure and enhances strength via intensified eta' precipitation, but compromises ductility due to residual eutectics. Critically, Y addition forms thermally stablized Al8Cu4Y phases that incorporate Fe impurities, mitigating their embrittling effect. The alloy with a Zn/Mg ratio of 3.5 achieves an optimal synergy, delivering a yield strength of 706 MPa and an elongation of 6.1%. This study clarifies the interaction between Zn/Mg-controlled precipitation and Y-containing intermetallics, offering a guideline for designing high-performance aluminum alloys.

Herein, low-Gd-content Mg-Gd-Zr system alloys with novel strength and adequate ductility were prepared by Nd and Y elements alloying combined with hot extrusion. The effects of Nd and Y elements on the microstructure, texture and mechanical properties of as-extruded Mg-6Gd-0.5Zr (VK61), Mg-4Gd-2Nd-0.5Zr (VEK421) and Mg-4Gd-2Y-0.5Zr (VWK421) alloys were investigated. The results showed that the addition of Nd not only refines and homogenizes the alloy structure but also promotes the dynamic precipitation of the secondary-phase particles during the extrusion process; while the addition of Y significantly inhibits the recrystallization behavior of the alloy during extrusion, forming a typical bimodal structure. After extrusion, the VK61 and VEK421 alloys consisted of fine dynamic recrystallization (DRX) grains while the VWK421 alloy consisted of fine DRX grains and coarse deformed grains. The as-extruded VEK421 alloy demonstrated optimal plasticity, characterized by a UTS of 245.4MPa and an EL of 33.6%. The as-extruded VWK421 alloy had the highest volume fraction of the second phase, the lowest recrystallization volume fraction, and the highest texture intensity. It also exhibited optimal tensile strength; ultimate tensile strength (UTS) and elongation (EL) were 261.6MPa and 18.2%, respectively, 66.7% and 106.8% higher than the as-solutionized alloy. The alloy-strengthening mechanisms mainly include fine grain strengthening and dislocation strengthening. Moreover, the presence of DRXed grains with a weak texture plays a significant role in improving the plasticity of the alloy.

Additive manufacturing technology is an effective approach to realize the integral forming of complex components of aluminum matrix composites (AMCs). However, the interfacial reaction between graphene nanoplatelets (GNPs) and the Al matrix is a key issue restricting their reinforcement efficiency. In this study, Cu powder was uniformly coated on the surface of GNPs by a wet mixing process, combined with multi-pass hot drawing plastic deformation, so that the GNPs–Cu powder was uniformly dispersed inside the Al wire. During the wire arc additive manufacturing (WAAM) process, the copper layer can effectively block the direct contact between GNPs and the Al matrix, thereby inhibiting the harmful interfacial reaction. The results show that in the 5 vol pct GNPs/AlCu composite, GNPs are uniformly distributed, and a large number of Al2Cu precipitates are formed around GNPs. There is no Al4C3 brittle phase generated at the interface, and the GNPs–Al interface is clean and intact. Benefiting from the above microstructural characteristics, the tensile strength and yield strength of the composite are increased by 42 and 37 pct compared with pure AlCu alloy, respectively. This work can provide a new idea and method for the additive manufacturing of high-performance AMCs.

Refractory high-entropy alloys (RHEAs) have emerged as a leading frontier in advanced alloy research due to their promising mechanical properties at both ambient and elevated temperatures. However, their widespread application is hindered by inherent limitations, including high density and the strength-ductility trade-off. In this work, a novel (Ti45Nb30Cr15V10)(96)Al-4 lightweight RHEA was designed and processed through grain refinement combined with the introduction of a small amount of C15 Laves precipitates. The as-cast alloy with a single body-centered cubic (BCC) phase shows a tensile yield strength of similar to 1018 MPa and a fracture strain of similar to 8.9%. After cold-rolling and subsequent annealing, the alloy develops a refined BCC matrix containing dispersed C15 Laves precipitates achieving an enhanced strength-ductility synergy with a tensile yield strength of similar to 1092 MPa and a fracture strain of similar to 14.1%. The underlying mechanism is primarily attributed to strong solid-solution strengthening and complex deformation behaviors, including multi-directional planar slip, cross-slip, and dislocation intersections, which are facilitated by grain refinement and the presence of C15 Laves precipitates.

The utilization of novel engineering materials like shape memory alloys has significantly broadened their application scope within civil engineering. Consequently, this study examines the mechanical performance of a grooved metallic-yielding damper fabricated from shape memory alloys. The seismic performance of the new system has been studied using the nonlinear static analysis method in ABAQUS software. Also, after a parametric investigation, the applicability of this kind of damper in a steel frame has been evaluated using the nonlinear dynamic analysis and considering the accelerograms of near-fault and far-fault earthquakes. The superelastic behavior of shape memory alloys has been applied to ABAQUS software by using the Brinson model and considering phase transformations. Lastly, the effect of various geometric parameters on the steel frame’s seismic performance, including stiffness, ductility, and energy absorption capability, has been studied. The results indicate that the ductility of the presented new damper is 56 and is greater than ductility of many conventional metal damper. Also, studied damper has great energy absorption and can easily replace other metallic-yielding dampers including ADAS and TADAS. Moreover, it is evident that the proposed system exhibits substantially enhanced energy absorption and ductility equated to the braced frame equipped with the equivalent steel damper, thus rendering it suitable for engineering applications.

ZL305 aluminum alloy is widely used in ship and marine engineering industry due to its high strength and ductility, and good corrosion resistance. As the main element in ZL305, Mg plays an important role at its mechanical and corrosion properties. This paper certifies that (1) as the Mg content increases, the casting mechanical property of ZL305 declines but the tensile strength and ductility significantly increase after T4 heat treatment process; (2) Despite these improvements, the higher Mg content is also associated with an increase in material porosity. Under the slow strain rate tensile stress corrosion condition, the intergranular fracture on the fracture surface and a proliferation of secondary intergranular cracks increase, which ultimately leads to the reduction of its stress corrosion resistance property. This study highlights the importance of modulating the Mg content in optimizing the properties of ZL305 to ensure a balance between its strength, ductility and stress corrosion resistance.

An investigation into the corrosion behavior of pure Mo50Re and rare earth oxide-doped Mo50Re, produced by spark plasma sintering, was performed in Ringer’s physiologic solution at a temperature of 37 °C. Potentiodynamic polarization testing indicated a reduction in corrosion current density from 3.1 μA·cm‒2 for the pure Mo50Re to 1.6 μA·cm‒2 for Y-doped, 1.5 μA·cm‒2 for La-doped, and 2.1 μA·cm‒2 for Y-La co-doped variants. Furthermore, electrochemical impedance spectroscopy revealed that the charge transfer resistance for the rare earth-doped alloys was higher, with values reaching up to 2.4 × 104 Ω·cm2 for Y-doped, 3.4 × 104 Ω·cm2 for La-doped, and 2.9 × 104 Ω·cm2 for Y-La co-doped materials, in contrast to the 1.7 × 103 Ω·cm2 resistance observed for the pure Mo50Re. The research highlights the significant enhancement in corrosion resistance conferred by the incorporation of rare earth elements, ascribed to their ability to refine the grain size and purify the grain boundaries.

This paper investigates the microstructure, texture, and mechanical properties of the Mg-4Zn-1Mn-0.5Ca alloy subjected to hot extrusion under varying conditions of temperature (260 °C, 300 °C, 340 °C) and extrusion speed (0.01 mm/s, 0.1 mm/s, 1 mm/s). The primary objective is to determine the optimal extrusion parameters within the selected experimental range for achieving superior mechanical properties. The results indicate that, when extruded at a constant speed of 0.1 mm/s, the alloy exhibits optimal performance at 340 °C, with a yield strength of 202 MPa, ultimate tensile strength (UTS) of 306 MPa, and elongation at fracture of 18.9%. A decrease in extrusion temperature leads to an increase in yield strength but a reduction in ductility. Specifically, the UTS reaches its peak at 342 MPa at 300 °C, while it drops slightly to 329 MPa at 260 °C. The final results show that the comprehensive mechanical properties of the Mg-4Zn-1Mn-0.5Ca alloy obtained by hot extrusion treatment with an extrusion temperature of 300 °C and extrusion speed of 0.1 mm/s are the best and can effectively improve the mechanical properties of the alloy and provide a good choice for the preparation of other biodegradable magnesium alloy products.

In the scope of this exploration, AZ61 magnesium matrix composites fortified with bimodal size SiC particles were synthesized using ultrasonic-assisted mixing in the semi-solid state, which exhibited optimal grain refinement and exceptional creep resistance. We examined the impact of bimodal SiC particles on the microscopic structure and creep deformation of the resulting composites. Our findings indicated that incorporating bimodal SiC particles resulted in the refinement of the matrix grains and alteration of the morphology of the Mg17Al12 phase. Furthermore, the micron-sized SiC particles exhibited a typical necklace-like particle distribution around the grain boundaries of the bimodal SiC particle/AZ61 composites, while the nano-sized SiC particles were mainly located around the micron-sized particles. As the volumetric percentage of micron SiC particles increased, the quantity of nano-sized particle clusters diminished noticeably. Creep analysis at 200 °C and 50 MPa revealed that the creep life of M−6+N−1 composite was increased by 111.9% compared to the AZ61 alloy. Additionally, the M−6+N−1 combination exhibited a significantly lower steady-state creep rate compared to the matrix alloy, with a reduction of approximately 11 times. These results indicate that the bimodal SiC particle/AZ61 composites have superior creep resistance, which is a consequence of the grain refinement and grain boundary pinning effects of SiC particles.

To investigate the influence of different crystal orientations of tantalum on corrosion performance, this study explored the diverse corrosion behaviors exhibited by the (110), (200), and (211) crystal planes of monocrystalline tantalum in a 3.5 wt% NaCl aqueous solution. The electrochemical behavior of the three crystal planes was characterized using open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy tests. The results revealed that the corrosion potential of the (110) crystal plane was slightly higher than that of the other two crystal planes, suggesting that this can be attributed to the influence of surface energy. The corrosion current density and corrosion rate of the (110) crystal plane were measured to be 0.269 mu A cm(-2) and 1.911 x 10(-3) mm/y, respectively, significantly exceeding those of the other two crystal planes. Additionally, the electrochemical impedance spectroscopy results indicated that the modulus impedance and polarization resistance of the (110) crystal plane were much lower compared to the other two crystal planes, suggesting inferior corrosion resistance. A comprehensive analysis indicates that the (110) crystal plane exhibits poorer corrosion resistance compared to the (200) and (211) planes, with the interplanar spacing identified as the primary factor influencing its corrosion resistance.

In this study, through reasonable composition design, three elements of Zn, Mn and Ca, which are harmless to human body, were selected for alloying magnesium. The effects of ECAP treatment on the microstructure and corrosion properties of Mg-4Zn-1Mn-0Ca, Mg-4Zn-1Mn-0.2Ca and Mg-4Zn-0Mn-0.2Ca alloys were studied. The corrosion mechanism of Mg-Zn-Mn-Ca alloys with different components in Simulated. Body fluid (SBF) was analyzed by weight loss method and electrochemical test. The grains and the second phase were refined by Equal Angular Channel Pressing (ECAP). It was found that after 8 ECAP deformations, the microstructure of the alloy was refined and more uniform than that of the extruded alloy. The corrosion resistance of the Mg-Zn-Mn-Ca alloy after ECAP deformation in simulated body fluids was studied by electrochemical testing techniques, immersion experiments and observation of the microstructure and morphology of corrosion products. The relationship between microstructure characteristics, the behavior of the magnesium metal matrix and the properties of corrosion products was revealed. The results show that the microstructure of the alloy is refined and the corrosion resistance is improved with the increase in extrusion passes in the SBF solution. The corrosion resistance of magnesium alloy after 8 ECAP deformation is the best, showing small Icorr and large Rt. With the extension of the soaking time, the surface of the alloy will form a passivation film, which will protect the matrix and avoid further corrosion of the alloy. It is found that in SBF, the corrosion of the alloy surface is mainly pitting, which indicates that Ca2+, HCO3- and HPO42- in SBF can reduce the corrosion rate of magnesium alloy.

The mechanical behavior and microstructure evolution of Al-Mg-Li alloys under the effect of electric current was investigated using an electropulsing-assisted uniaxial tensile (EAUT) test combined with microstructure observations. It was found that the localized Joule heating-induced microscale high temperature at the grain boundaries in the necking zone significantly accelerated the grain boundary weakening when necking occurred, which resulted in rapid intergranular fracture and relevant decrease in elongation. Electropulsing induced continuous dynamic recrystallization (CDRX) in the both side layers and the discontinuous dynamic recrystallization (DDRX) in the intermediate layers of the Al-Mg-Li sheet during EAUT testing at 460 degrees C and higher, promoting the formation of newly near-equiaxed recrystallized grains and weakening of beta-fiber texture components. For the conventional high temperature tensile test, only a small amount of recrystallized grains formed along the grain boundaries of the coarse parent grains under the control of DDRX. The occurrence of CDRX during EAUT was substantially attributed to the promoted effect of electropulsing on dislocation glide and climb, which resulted from the combined effect of microscale localized Joule heating around dislocations and the electro-induced enhancement effect on vacancy diffusion. (c) 2021 Elsevier B.V. All rights reserved.

The as-cast microstructure of a typical hypereutectic Al-25Si alloy was studied, and the growth mechanism of different primary silicon phases was analyzed. The results show that the as-cast microstructure phase composition of the alloy is mainly primary silicon and eutectic silicon. Primary silicon is mainly petal-like, massive and other complex polyhedrons, and there are a lot of cavities, cracks and other defects in the interior and boundary; Eutectic silicon is coarse and long needle-like, and the distribution is relatively messy, which seriously deteriorates the mechanical properties and cutting performance, and hinders the further application of the alloy in the field of lightweight pistons. Petal-shaped primary silicon is grown by combining five tetrahedral crystal nuclei in the melt into a decahedron, while bulk primary silicon is mainly caused by the unbalanced aggregation of impurity elements. And these two types of silicon phase growth methods are related to the twin groove growth mechanism, which is the result of a combination of multiple mechanisms.

In mechanical engineering and intelligent manufacturing research area, excellent surface quality and dimensional accuracy at the macro level for products manufactured by means of information and intelligent technology are desired, at the same time, their controls of microstructure and properties at the microscopic scale are also of great concern. Tantalum-tungsten (Ta-W) alloy components are widely used in high temperatures, ballistics, and aerospace fields due to their advantages of high density, high plasticity, and good corrosion resistance. Therefore, in this paper, by studying the influence of processing parameters of heat treatment on microstructure and properties in cold forging deformation, tantalum-tungsten alloy components with homogeneous and fine-grained microstructure as well as excellent mechanical properties can be successfully achieved. Results show that the average grain size of Ta-W alloy components reaches the minimum when annealed at 1300 °C for 60 min, which is less than 25 μm. The recrystallization process of Ta-W alloy components with a reduction of 74% has completed at the annealing temperature of 1300 °C, and apparently grain growth occurs when the annealing temperature reaches 1400 °C. With the increase of annealing temperature paremeters, the microhardness of Ta-W alloy components decreases at first then slightly increases. The increase of microhardness at 1400 °C is likely due to the tendency of refractory metals to oxidize at high temperatures. After annealing treatment, the deformation of Ta-W alloy components shows obvious elastic-plastic deformation behavior, and its elongation reaches a maximum value of 46%.

The bulk Cu billets with ultrafine-grained microstructure were successfully processed from full-annealed coarse grained oxygen-free high conductivity (OFHC) Cu by the cyclic extrusion and closed compression (CECC), subsequently annealed at different temperatures. The evolution of the microstructure and mechanical properties was systematically studied. The results show that the effective strain per CECC process is ε=2.77, with further annealing treatment, a high-efficiency grain refinement is realized. After two cycles of CECC process and annealing at 350 °C for 1 h, the grain size refined to ～3 μm, the tensile strength increased to 280 MPa with a high ductility of 54%. Furthermore, a homogeneous structure and mechanical properties in the bulk copper billets for post-forging could be obtained.

Abstract The effects of the main process factors such as temperature and time on the microstructure and properties of hypereutectic Al-20Si-1.5Mg alloy were analyzed. The results show that when the solution treatment process is 510 °C × 6h, the primary silicon, eutectic silicon and Mg2Si in the sample structure have been solution maximized, and the morphology distribution has been optimized, which is related to the passivation effect of solution treatment on silicon phase, etc.; At the same time, the hardness decreases first and then increases with the extension of solution time, and the inflection point appears at 6h. Compared with the as cast structure, the hardness is reduced by more than 15%. At this time, the super saturation of the alloy is the largest, which is conducive to obtain the best aging strengthening effect.

The effects of Mg Addition mode and amount on the microstructure and mechanical properties of hypereutectic Al-25Si alloy after modification were analyzed. The results show that the Mg 2 Si phase is relatively small, which is in the shape of granular or small bone, and has relatively little damage to the tissue; The hardness of the alloy is directly proportional to the amount of Mg added. When 1.5wt. % Mg is added, the microstructure and properties reach the best state. If the amount of Mg 2Si is excessive, it will gradually change into a coarse mesh, Chinese character shape and deteriorate the properties. The main reason is that there is a close adhesion growth relationship between Mg 2 Si and eutectic silicon. The modification and refinement lead to the lack of nucleation basement and the inhibition of growth of Mg 2 Si. At the same time, the modified residual AlP phase is used as the nucleation point. Mg 2 Si phase did not coarsen obviously, and other phases also maintained in a good shape.

In this study, a new type of external added nano-sized SiC particles (SiCnp for short) and in-situ Mg2Si particles reinforced composites, i.e. (1.5 wt% Mg2Si + 1 wt% SiCnp)/Al-Cu composites, has been successfully prepared for the first time, and the microstructure and mechanical properties of the composites are studied. The eutectic Mg2Si phase in the Mg2Si/AI-Cu composites is refined from short strip with length of about 10 mu m to dot shape with diameter of about 2 mu m in (Mg2Si + SiCnp)/Al-Cu composites, which is uniformly distributed inside Al2Cu phases precipitated at the grain boundary. The alpha-Al grains are also significantly refined. It is also first discovered that SiCnp can act as nucleus of Mg2Si, or be captured by the Mg2Si phase during solidification, which promotes the heterogeneous nucleation of the eutectic Mg2Si phase to reduce the size of Mg2Si phase. The ultimate tensile strength (UTS) and yield strength of (Mg2Si + SiCnp)/Al-Cu composites are 325 MPa and 210 MPa, which are 3.2% and 28.8% higher than those of Mg2Si/AI-Cu composites, respectively. These properties are also improved by 20.4% and 21.4% respectively compared with SiCnp/Al-Cu composites, while (Mg2Si + SiCnp)/Al-Cu composites maintain good ductility.

在树脂砂中加入石墨粉和锆砂,利用导热系数仪测量砂型导热系数,研究了锫砂和石墨粉的含量对铸型导热系数的影响,进行了实验验证,与Maxwell模型模拟计算的导热系数进行对比研究.结果 表明,在石墨粉含量为8％、锫砂含量为30％时,砂型导热系数达到最大值,与树脂砂型相比导热系数提高了90％;混合砂型的晶粒比树脂砂型的细4μm.混合砂型浇注得到的铸件的抗拉强度比树脂砂型的抗拉强度高3％～4％,伸长率下降了0.8％～0.9％.

对AZ80-4Sn镁合金的凝固过程进行了不同频率(处理频率分别为0、300和600 Hz)的脉冲电流处理,以了解电脉冲对其微观组织及力学性能的影响.结果 表明,电脉冲处理可以细化镁合金的凝固组织,并优化其力学性能,且在一定范围内,随着脉冲频率增加,AZ80-4Sn镁合金的组织及性能逐渐得到改善.与未进行脉冲处理的AZ80-4Sn合金相比,当对其施加600 Hz的电脉冲处理后,粗大的树枝晶结构被细化,二次枝晶间距减小,较大的块状Mg2 Sn相得到细化并且在基体中较均匀分布.经脉冲处理后,合金抗拉强度与伸长率分别由101 MPa和2％提高至173MPa和2.6％,分别提高了71.3％和30％.