Al/Mg bimetallic materials combine the excellent properties of aluminum and magnesium alloys, offering the promising application prospects in aerospace and other fields. Diffusion bonding is one of the most effective methods for fabricating the bimetallic materials. However, the tendency for brittle Al–Mg intermetallic compounds to form at the interface significantly reduces the bonding strength. To address this issue, the Ni/Cu composite interlayers were introduced at the Al/Mg bimetallic interface to achieve the solid/liquid diffusion bonding. The effects of holding time on the interfacial microstructural evolution and bonding strength were systematically investigated. The results show that at the bonding temperature of 500 ℃, the eutectic reaction occurs between the Mg matrix and the Cu foils, promoting the liquid-phase diffusion at the interface, while the solid-state diffusion takes place between the Ni foils and the Al matrix. As the holding time increases from 15 min to 30 min, the Cu foils are gradually consumed and eventually disappear. When the holding time reaches 45 min, the wavy interface morphology begins to form. The maximum shear strength of 53.78 MPa is achieved after holding for 60 min, the interfacial structure is composed of Al/Al3Ni2+Al3Ni/Ni/Mg2Ni/Mg3AlNi2/Mg, and the fracture occurs near the interface between Mg2Ni and Mg3AlNi2.

The integration of dissimilar metals is a key strategy for developing lightweight structural materials, where the reliability of interfacial bonding critically determines mechanical performance. In Ti-Al systems, intermetallic compounds (IMCs) govern load transfer and fracture behavior. However, their evolution in Mg-containing Al alloys remains insufficiently understood, despite Mg being a common alloying element. In this work, solid-state diffusion bonding between TC4 Ti alloy and 2A12 Al alloy was conducted at 475-550 degrees C to investigate the evolution of interfacial microstructures and their correlation with mechanical performance. A double-layered interfacial structure consisting of Al3Ti and Al18Ti2Mg3 was formed. With increasing temperature, the interfacial structure evolves from an Al18Ti2Mg3-dominated configuration to an Al3Ti-dominated configuration, which is associated with enhanced Ti diffusion. This transition leads to distinct fracture behavior under different loading conditions. Under shear loading, the fracture-controlling region shifts to the Al3Ti layer as it becomes continuous, accompanied by an increase in shear strength from 81.54 MPa to 127.62 MPa. In contrast, under tensile loading, crack propagation preferentially occurs along the Al18Ti2Mg3 layer, which provides a relatively continuous path for crack growth along the interface. This behavior reflects that interfacial fracture behavior in Mg-containing Ti-Al systems is closely related to phase competition and the structural continuity of interfacial phases.

Composite materials combining titanium (Ti) and magnesium (Mg) alloys promise synergistic benefits-lightweight, high strength, corrosion resistance, and biocompatibility, but their development is stymied by the inability of Ti and Mg to form a strong metallurgical bond. To address this issue, a two-step method is proposed: first diffusion-weld the Ti mesh to the TC4 substrate, then hot-press sinter AZ91 Mg alloy into the mesh pores to form a three-dimensional(3D) interlocking interface. The resulting 3D interlock mechanically locks the two phases, redirecting load away from the inherently weak Ti-Mg phase boundary into the stronger Ti mesh and Mg matrix. Finite-element analysis and microstructural characterization confirm this transition from a planar to a volumetric stress field. Under optimized conditions, the interface attains a tensile strength of 147.8 MPa (66.8 % of the Mg matrix) and a shear strength of 110.5 MPa (84.8 % of the Mg matrix), substantially outperforming conventional flat-interface joints. Beyond the Ti-Mg system, this design paradigm can be extended to bond dissimilar metals with weak metallurgical affinity-or even metal-nonmetal hybrids-provided the 3D-skeleton phase remains intact during densification, thereby offering a generalized solution for high-performance interfaces in multi-material assemblies.

In this paper, the problems of bending and edge cracking in the 2A12-Al/AZ31-Mg laminated metal composites (LMCs) prepared during roll bonding (RB) were studied systematically. The results show that the formation of bending and edge cracks is due to the difference in microstructure and mechanical properties between as-sintered 2A12 aluminum alloy (S-2A12-Al alloy) and as-sintered AZ31 magnesium alloy (S-AZ31-Mg alloy). This leads to the different plastic deformation ability of the two alloys, and they cannot achieve synergistic deformation during RB. The synergistic deformation of the two plates can be achieved by pre-rolling deformation and annealing treatment before RB. This can effectively solve the bending and edge crack problems of 2A12-Al/AZ31-Mg LMCs during RB. Therefore, the S-2A12-Al alloy was first pre-rolled with 40

Al/Mg bimetallic materials combine the complementary advantages of aluminum and magnesium alloys, demonstrating significant potential for lightweight structural and aerospace applications. However, the formation of brittle intermetallic compounds at the Al/Mg interface during diffusion bonding severely weakens interfacial bonding strength. To address this issue, the Ni/Cu composite interlayer was introduced to simultaneously achieve solid-state diffusion with the Al matrix and liquid-phase-assisted diffusion with the Mg matrix, thereby tailoring the interfacial structure and enhancing mechanical performance. The results reveal that as the bonding temperature increases from 460 degrees C to 500 degrees C, the Ni/Al interface consistently remains in a solid-state diffusion regime, while the Cu foil at the Mg side undergoes a transition from solid-state to liquid-phase diffusion, forming a Mg-Cu eutectic liquid. This transient liquid phase improves interfacial wettability, facilitates atomic transport, and is subsequently extruded under applied pressure. As a result, a three-dimensional wavy interface morphology develops on the Mg side, accompanied by the formation of Mg3AlNi2 and Mg2Ni intermetallic layers. At 500 degrees C, the Al/Mg interface evolves into a multilayered structure comprising: Al/Al3Ni2 + Al3Ni/Ni/Mg2Ni/Mg3AlNi2/Mg, achieving a maximum interfacial shear strength of 53.78 MPa. Fracture analysis indicates that failure occurs between the Mg3AlNi2 and Mg2Ni phase layers. These findings demonstrate that the Ni/Cu composite interlayer effectively suppresses the direct reaction between Al and Mg, achieving synergistic enhancement through solid-state diffusion on the Al side and liquid-phase diffusion on the Mg side.

Co-based diamond tools are widely appreciated for their exceptional mechanical properties and good holding ability for diamonds. However, the reliance on cobalt (Co) poses challenges due to its high cost and scarcity as a strategic resource. A potential alternative is the Fe–Co–Cu alloy, emerging as a promising substitute for Co matrix alloys. In this work, hot-press sintering was utilized to create pure matrix and diamond tools utilizing Fe–Co–Cu pre-alloyed powders of varying compositions as raw materials without the use of any sintering additives. The investigation explores the influence of different Fe: Cu ratios on the mechanical properties of diamond tools produced from Fe–Co–Cu alloys, focusing on the diamond holding force, microstructure, and phase structure evolution. Results indicate that at a Co content of 15 wt% and Fe: Cu ratios ranging from 7.5:1 to 1:7.5, the Fe–Co–Cu alloy's phase structure primarily comprises α-Fe and a Cu-rich phase. Co predominantly exists in α-Fe as a solid solution. As the Fe: Cu ratio decreases, the alloy's phase structure gradually transitions from α-Fe to a Cu-rich phase, accompanied by a progressive decline in both bending strength and hardness, while the densities gradually increase. The matrix's holding force on the diamond exhibits an increasing and then diminishing trend, peaking at the Fe: Cu ratio of 6:1. The Fe–Co–Cu alloy sintered by hot-pressing has a nearly equiaxed grain structure with no obvious texture.

Due to its excellent performance of lightweight and high strength, Al/Mg bimetal has high application value in the aerospace field. However, the poor bonding quality of the Al/Mg bimetallic interface is still an urgent problem to be solved. Therefore, this paper proposes to use Ni foil as the interlayer to control the interface structure and improve bonding strength. The results show that the Ni interlayer has a positive influence on Al/Mg interface structure regulation. The interface is composed of Al 3 Ni, Al 3 Ni 2 and Mg 2 Ni phases, and no Al–Mg brittle intermetallic compounds (IMCs) are formed. Meanwhile, the Mg 2 Ni phase is distributed as islands on the interface at 490 °C, effectively preventing crack propagation. The average shear strength of the interface reaches a maximum of 69.5 MPa. Besides, the interface fracture mechanism was deeply analyzed. The Al/Ni interface has excellent bonding performance, and the fractures occur at the Mg/Ni interface. The fracture mode from intergranular and cleavage mixed fracture at 490 °C to brittle cleavage fracture at 505 °C.

In this work, Al2O3 ceramic coatings were prepared the surface of powder metallurgy (PM) 2024 aluminum alloy via the micro-arc oxidation (MAO) technique. The effects of the current density and the oxidation treatment time on the microstructure and properties of the MAO coatings were investigated. The results reveal that the oxide film mainly comprises the γ-Al2O3 phase, the amorphous Al2O3 phase, and a small amount of the mullite phase. There are traces of W in the coatings, which exist in the form of W, WO3, and W18O49. With increasing current density, the thickness and surface roughness of the MAO coatings prepared on the PM 2024 alloy increase, while their surface hardness first increases and then decreases. The increase in the current density promotes the transformation of the amorphous Al2O3 phase into the γ-Al2O3 phase. The maximum hardness value of 1270 HV is obtained at a current density of 20 A dm−2. The MAO coatings provide superior corrosion protection for the PM 2024 aluminum alloy, and the MAO coatings obtained at a current density of 15 A dm−2 exhibit the highest corrosion resistance.

The Al/Mg alloy were successfully prepared by the combined method of powder metallurgy and rolling. The microstructure and interface bonding strength of the Al/Mg interface under rolling and annealing temperatures were investigated. The results indicates that, the Al/Mg interface is only physically bonded after rolling, but metallurgical bonding can be achieved after annealing. When the annealing temperature is 200 degrees C, the shear strength of Al/Mg interface is the maximum, which is 37.06 MPa. With the increase of annealing temperature, the thickness of interfacial layer increases gradually. When the annealing temperature was 400 degrees C, a typical three-layer structure was formed in the Al/Mg interface. Micro-area XRD analysis showed that Mg32Al47Cu7, Al3Mg2 and Al12Mg17 phases were generated at the interface.

The objective of this paper was to assess the coupling effect of vacuum, pressure and temperature on microstructure and mechanical properties of PM aluminum alloy. The results showed that the densification of PM aluminum alloy mainly depended on the powder plastic deformation caused by hot pressing, but the state of particle boundary (PB) was affected by vacuum besides temperature and pressure. When the powder was sintered under high vacuum of 10(-3) Pa, the oxide film at PB could be disrupted by pressure, resulting in the formation of narrow regions of metal/metal contact. While under low vacuum of 10(-1) Pa, the oxide film coarsened by secondary oxidation was unable to be broken by powder compressing, resulting in residual microcracks and segregation of second phases at the PB. This seriously weakened mechanical properties of PM aluminum alloy. The eutectic liquid formed by increased temperature would make the above process more complex.

To improve the microstructure compactness and mechanical properties of powder metallurgy (P/M) AZ31 magnesium alloy, hot rolling deformation was carried out in this work. The effect of rolling reduction on the microstructure and mechanical properties of P/M AZ31 magnesium alloy was investigated systematically. The results show that the equiaxed-shape prior particles gradually elongated along the rolling direction and evolved into banded-shape with the increase of rolling reduction. The grains with random orientation distribution gradually evolved into preferred orientation distribution, and the grain size gradually decreased. When the rolling reduction increases from 0 to 80%, the relative density, ultimate tensile strength and Vickers hardness increase from 98.03%, 244.37 MPa and 55.95HV to 98.5%, 296.56 MPa and 66.89HV, respectively, while the elongation decreases from 22.97% to 12.22%. A strong basal texture with (0001) basal plane parallel to the rolling surface was mainly formed in the alloy after hot-rolling. The improvement of mechanical properties of the alloy after hot-rolling was mainly due to the increase of microstructure compactness and fine grain strengthening. When the rolling reduction was small, the deformation was mainly dominated by slip and twinning; while when the rolling reduction was large, the deformation was mainly dominated by slip and dynamic recrystallization.

The hypervelocity impact of space debris causes damage or destruction to spacecraft. The continuous damage caused by space debris creates greater requirements for protective materials. Wave-impedance gradient-protection material is a new type of space-debris-protection material with high kinetic-energy dissipation. However, the relationship between the distribution characteristics of the impedance layer and the protective performance is still unclear. This study provides guidance for the design of high-performance wave-impedance gradient materials by establishing the quantitative relationship between impedance-layer distribution characteristics and protective performance. Based on the one-dimensional shock-wave theory, this paper analyzes the propagation process of shock waves in wave-impedance gradient materials, establishes a transmission model of shock waves with changes in impedance layers, and quantitatively studies the influence of the change in wave impedance on the impact pressure, internal-energy conversion, and projectile- breaking characteristics by means of a numerical simulation. The results show that, when the surface and back of the wave-impedance gradient material are titanium alloy and nylon, respectively, the total transmission coefficient increases from 0.206 to a maximum of 0.339 with the continuous change in the gradient. The reduction amplitude of the shock wave with time under the three working conditions is Ti-Al-Mg-Ny > Ti-Al-Ny > Ti-Ny. The relationship of the transformed internal energy is Ti Al-Mg-Ny > Ti-Al-Ny > Ti-Ny, and the projectile breaking area is Ti-Al-Mg-Ny > Ti-Al-Ny > Ti-Ny. The analysis shows that the continuous change in wave impedance is beneficial to reduce the attenuation of the amplitude of the shock wave in the hypervelocity projectile, to keep the stress amplitude of the shock wave at a higher level, and to improve the internal-energy conversion and impact-breaking degree of the projectile, thereby enhancing the protection performance of the wave-impedance gradient material.

Powder byproduct is inevitably produced during spray-forming of 7055 aluminum alloy, greatly reducing the utilization rate of raw materials and increasing production costs. To make such powder byproduct into valuable products, 7055 alloy was prepared by hot-press sintering of powder byproduct in this work. The characteristics of the powder byproduct were studied comprehensively. The microstructure and properties of the as-sintered 7055 alloy were investigated, and the parameters of the hot-press sintering process were optimized using the Taguchi method. The results indicated that the microstructure of the as-sintered alloy was very compact and the grains typically had equiaxed structure, with the main precipitated phase being MgZn2. The tensile strength of the alloy prepared by hot-press sintering with parameters of sintering temperature of 560°C, holding time of 150 min, and pressure of 12 MPa was 287.29 MPa.

To efficiently reuse the powder by-products produced during the production of the spray-formed 7055 alloy, a 7055 aluminum alloy was prepared by traditional powder metallurgy by using powder by-products as the raw materials. In addition, characteristics of the powder by-products and effects of the sintering conditions on the microstructure and properties of the 7055 Al alloy are investigated. The densification mechanism of the powder by-products during sintering is revealed. The results indicated that the existence of an oxide layer on the particle surface of the powder by-product as well as pores inside the particles. The shrinkage and densification of the sintered body during vacuum sintering is hindered by the oxide layer, and lead to a low relative density and strength. However, the shrinkage and the densification of sintered body are promoting by the fracture of oxide layer under the pressure during hot-press sintering, and result in a high relative density and strength. At a temperature of 550 degrees C, a pressure of 12 MPa, and a holding time of 120 min, the as-sintered 7055 alloy with the relative density of 99.70% and the ultimate tensile strength of 277.72 MPa are obtained.

This paper proposed a novel low-pressure sintering process contraposing to characteristics of pre-alloyed aluminum powders and analyzed its feasibility. The low pressure was set to 0.1 MPa in this study. Meanwhile, 0 MPa and 10 MPa were set as control group. With gas-atomized 2024 aluminum powders as raw material, the microstructure and tensile properties of specimens sintered under three orders of magnitude of pressure (0 MPa, 0.1 MPa and 10 MPa) at two representative temperatures (525 °C and 575 °C) were compared. The results showed that it was difficult for pressureless sintering (0 MPa) to densify pre-alloyed aluminum powders, but low-pressure sintering could. As the liquid phase formed at supersolidus temperature was squeezed out, the loss of alloying elements such as Cu and Mg, which would play an important role in subsequent heat treatment, during low-pressure sintering was apparently less than that of 10 MPa. The density of aluminum sintered under 0.1 MPa at 575 °C was 2.732 g/cm3 and the ultimate tensile strength was 228.16 MPa with ductility of 12 %, which achieved a good balance of plasticity and strength. These findings will bring new insights to the industrialization of aluminum powder metallurgy (APM).

Magnesium and its alloys have become attractive materials in automotive and aerospace fields because of their low density and high strength. However, their application is greatly limited by their poor deformation capacity. Powder metallurgy technology can reduce the deformation and processing of magnesium alloys during the preparation process to alleviate this problem because of its near net shape machining characteristics. In this paper, a high-performance AZ31 magnesium alloy was prepared via vacuum hot-press sintering. The effects that sintering temperature has on the structure and mechanical properties of the assintered alloy were investigated. The results indicate that the sintered microstructure is composed of approximately equiaxed alpha-Mg crystal grains, and nanoscale Al-Mn phases precipitated in the crystals and particle boundaries. At an optimal sintering temperature of 535 degrees C, the average tensile strength, compressive strength, elongation, and fracture strain of the sample are 247.10 MPa, 391.35 MPa, 22.27%, and 24.17%, respectively. In addition, the reasons for the high strength and favorable elongation of the AZ31 magnesium alloy that was sintered via vacuum hot pressing were also analyzed. This is mainly because pressure is applied during the sintering process; this eliminates pores and breaks the oxide film on the powder surface, thereby forming a good metallurgical bond between the powders. (c) 2021 Elsevier B.V. All rights reserved.

To effectively improve the mechanical properties of 7055 aluminum alloy prepared by powder by-products, aging treatment was carried out on the as-sintered 7055 alloy. The effects of different aging treatment parameters on the microstructure, mechanical and corrosion properties of the as-sintered 7055 alloy were investigated. The results show that the microstructure of as-sintered alloy is still a typical equiaxed crystal structure after aging treatment, however, the number of precipitated phases in matrix was significantly reduced and in uniformly fine needle-like distribution. The metastable eta' phase is mainly precipitated. Moreover, the strength of the aging treated sample is nearly doubled in comparison to that of the as-sintered alloy, and the sequence of the strength of three aging-treated sample is: RRA > DA > T6. The improvement of mechanical properties of the aging-treated sample is mainly attributed to the precipitation strengthening. Furthermore, the corrosion resistance of three aging-treated sample follows: DA > RRA > T6, and the continuous grains boundary precipitations and Fe-containing precipitates increase the corrosion susceptibility.

Herein, an 2024-Al/AZ31-Mg laminated composite was prepared by hot-pressing sintering using powder metallurgy integrated forming and sintering. Effects of sintering temperature on the microstructure and mechanical properties of the matrix and interface of Al/Mg laminated composites were investigated. The mechanisms of interface formation and evolution were obtained. The results indicate that with sintering temperature increases from 475°C to 550°C, the densification of the Al/Mg matrix gradually increases. Intermetallic compounds were generated at the interface, and their thickness increased from 56.4 μm to 195.1 μm. In addition, the interface structure was composed of an Al7Cu3Mg6, Al3Mg2 and Al12Mg17 layer.At a sintering temperature of 525°C, the tensile strength and interface shear strength of Al/Mg laminated composites were 37.8 MPa and 31.13 MPa, respectively. The shear fracture occurred between the Al3Mg2 layer and Al12Mg17 layer and was a mixed cleavage and intergranular fracture.

In order to solve the problem of edge cracking of the as-sintered 2024 aluminium alloy during cold rolling, the initiation mechanisms of edge cracking were studied. The results indicate that the "herringbone" crack parallel to the rolling direction and the "zigzag" crack perpendicular to the rolling direction easily formed during cold rolling. The former mainly occurred during the early stage of cold rolling and was related to the poor plasticity of the as-sintered alloy and the stress state at the end of the rolled plate, whereas the latter appeared in a sample with a rolling reduction of more than 60%, mainly because the grains at the edge of the sample were subjected to three-direction shear stress, which results in cracking along the grain boundaries. However, both herringbone and zigzag cracks propagated along the grain boundary. Finally, the crack-free products were obtained by optimizing the cold rolling process.