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The effects of heat extrusion processing of spray forming TiCp/ZA35 composites on extrusion ratio, extrusion specific pressure, extrusion temperature and extrusion rate had been studied by artificial neural network (ANN). The artificial neural network model was created for heat extrusion processing. The input parameters of the ANN model were extrusion ratio, extrusion specific pressure, extrusion temperature and extrusion rate. The output of the ANN model was ultimate tensile strength. The model can be used for the prediction of properties of spray forming TiCp/ZA35 composites as functions of processing parameters. It can also be used for the optimization of the processing parameters. The ANN results are in good agreement with experimental phenomena, the biggest relative error and coincidence rate is less than 1.8% and 0.986. The optimized heat extrusion ratio, extrusion specific pressure, extrusion temperature and extrusion rate are 22415 MPa, 315 ℃ and 8 mm·s−1 respectively, and the tensile strength of spray forming TiCp/ZA35 composites is 486.7 MPa. The reinforcement phase MnAl6 whisker or particle is precipitated in the grains due to the indirect aging treatment of composites by hot extrusion. Dispersion strengthen and dislocation strengthen contribute a combination factor to increase the room temperature mechanical properties of the hot extruded TiCp/ZA35 composites, which is 38.3% higher than that of TiCp/ZA35 composites without heat extrusion.

The effects of heat extrusion processing of spray forming TiCp/ZA35 composites on extrusion ratio, extrusion specific pressure, extrusion temperature and extrusion rate had been studied by artificial neural network (ANN). The artificial neural network model was created for heat extrusion processing. The input parameters of the ANN model were extrusion ratio, extrusion specific pressure, extrusion temperature and extrusion rate. The output of the ANN model was ultimate tensile strength. The model can be used for the prediction of properties of spray forming TiCp/ZA35 composites as functions of processing parameters. It can also be used for the optimization of the processing parameters. The ANN results are in good agreement with experimental phenomena, the biggest relative error and coincidence rate is less than 1.8% and 0.986. The optimized heat extrusion ratio, extrusion specific pressure, extrusion temperature and extrusion rate are 22415 MPa, 315 ° C and 8 mm•s-1 respectively, and the tensile strength of spray forming TiCp/ZA35 composites is 486.7 MPa. The reinforcement phase MnAl6 whisker or particle is precipitated in the grains due to the indirect aging treatment of composites by hot extrusion. Dispersion strengthen and dislocation strengthen contribute a combination factor to increase the room temperature mechanical properties of the hot extruded TiCp/ZA35 composites, which is 38.3% higher than that of TiCp/ZA35 composites without heat extrusion. [ABSTRACT FROM AUTHOR]

The study focused on investigating the impact of rare earth element Gd content on both the microstructure and mechanical properties of FeCrNiCuTi 0.4 Gd x (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.1, 0.12, and 0.15, in mole ratio) high-entropy alloys, as well as elucidating the underlying mechanisms involved. The microstructure analysis revealed that the alloy exhibited a diphase structure consisting of FCC and BCC phases at low Gd content, and precipitation of the Cu 5 Gd phase occurred alongside the FCC and BCC phases at x = 0.05. The phase evolution of the current alloy system was assessed using the Ω - δ, △χ, and VEC (valence electron concentration) criteria. The mechanical properties indicated that the Vickers hardness increased with the increase of Gd content. Additionally, the compressive strength, yield strength, and plastic strain exhibit an initial increase followed by a decrease, while the average friction coefficient and wear demonstrated an initial increase followed by a subsequent decrease. The fracture mechanism shifted from plastic fracture to ductile fracture, ultimately transitioning to dissociative fracture with ductile fracture as the predominant mode. Similarly, the wear mechanism progressed from abrasive wear to a combination of abrasive wear with oxidation wear. The strengthening mechanisms of the present alloys included solid solution strengthening, fine crystal strengthening, and second-phase strengthening. • Rare earth element Gd was doped in FeCrNiCuTi 0.4 HEA. • Doping Gd improved the hardness, strength, and wear resistance of the HEAs. • The mechanisms included solid solution, fine crystal and second-phase strengthening. [ABSTRACT FROM AUTHOR]

Cellular materials with smooth profiles, improved structural strength, and reduced elastic-anisotropy are eternal pursuit in bone-implant filed. However, it is a huge task to meet so many requirements. In this work, a novel class of mechanical metamaterials, named as crystal sheet lattices, were proposed. The elastic performances were investigated using representative elementary volume model and examined by quasi-static compression tests. The plastic performances and energy absorption behaviors were experimentally calibrated. Meanwhile, elastoplastic simulations were adopted to study the deformation mode on the structural strengthen mechanism. The results demonstrate that the reduced elastic-anisotropy can be achieved without complicated regulation process. Under the same material volume fraction, the stiffness, yield strength, and energy absorption capability were respectively increased about 30%–60%, 30%–150%, and 70%–280%, for most of crystal sheet lattices in comparison with their truss-based counterparts. Being open type cellular materials, the crystal sheet lattices are of high mass-specific mechanical performances. Due to the smooth profiles, large surface volume ratios, and enhanced mechanical performances, CSLs also have potentials to be utilized in lightweight and heat transportation fields.

In order to insure atmospheric resistance and weldability, the carbon content of weathering steel was decreased. At the same time, increases in Mn content and V-N micro-alloying were adopted to increase the strength of weathering steel in this paper. The results indicate that when the mass fraction of Mn is 1.36%, the yield strength increases to 435 MPa, and the contribution of fine grain strengthening and dislocation strengthening to the yield strength is 59.8%. When the yield strength reaches 555 MPa, V-N alloyed weathering steel has good precipitation strengthening and fine grain strengthening effects, and the sum of the two mechanisms contributes more than 70% of the yield strength of the two groups of V-N alloyed weathering steel.

The present research was motivated by two unsettled questions. First, what are the detailed characteristics of the nanostructured interface in a nano-carbon/metal composite containing interfacial reaction products? Second, what other factors in interfacial carbide (not only its content) can influence the interface strength and mechanical properties, and if it is true? We developed a novel strategy to uncover these issues in graphite nano-flakes (GNFs)/Ti composites. Four GNFs/Ti samples with similar concentration of interfacial carbides were prepared under the guidance of DICTRA simulation. High-resolution transmission electron microscopy and precession assisted electron diffraction were applied to gain fundamental insight into the mechanisms that affect the characteristics of GNFs/Ti interfaces. The tensile results showed that the interfacial morphologies, GNFs-TiC x bonding strength, preferred orientation and growth defects were significant factors that were closely associated with the mesoscopic mechanical behavior. Interestingly, the heat-treated (HT) 1123K-600s GNFs/Ti composite exhibited the optimal tensile properties and superior GNFs-TiC x "synergetic" effect. The origin of such findings were explored from the viewpoint of nano-cracks/dislocation-interface interaction. This work provides a new insight in understanding the interfacial characteristics of GNFs/Ti composite, and underscores the importance of reaction interface design in strengthening of bulk GNFs/metal composite. Image 1 [ABSTRACT FROM AUTHOR]

Discontinuously reinforced 3D network structured Ti6Al4V (TC4) matrix composites with multilayer graphene (MLG) were fabricated via 3D dynamic mixing and spark plasma sintering (SPS) at high pressures (250–500 MPa). The interface microstructure, mechanical properties and strengthening mechanisms were systematically studied with various MLG contents. Experimental results exhibited that MLG can be relative uniformly dispersed onto the surface of TC4 powders by the 3D dynamic mixing method, SPS parameter of 700 °C-500 MPa caused weak interface bonding between MLG and Ti matrix, and 900 °C-250 MPa was determined as the optimal sintering condition. Appropriate ratio of in-situ generated TiC phase with approximately 30 vol% retained MLG at the interface was beneficial to the interface bonding. The compressive strength of the composites was remarkably enhanced with excellent compressive ductility. Superior mechanical properties with the highest strengthening efficiency (65.5%) and tensile strength, acceptable tensile ductility (9.0%) and higher Vickers microhardness were achieved in the 0.15 wt% MLG composites due to its better interface microstructure. The network interface strengthening mechanism by the TiC phase and residue MLG is proposed to be the dominant mechanism with a few contributions from C solid solution and fine-grain strengthening.

An increasing number of reports have demonstrated enormous strength enhancements in titanium matrix composites (TiMCs) reinforced with graphene nanoflakes (GNFs) on account of the superior mechanical properties of GNFs. Unfortunately, the difficulty of uniform dispersion and severe interfacial reaction are simultaneously the most challenging and serious issues in GNFs reinforced TiMCs. In this work, we applied electroless plating method to prepare Ni decorated GNFs (Ni-GNFs) as a reinforcement in Ti matrix to uniformly disperse the GNFs in Ti matrix and relieve the severe interfacial reaction between metal and carbon nanophase. The composite reinforced by low content Ni-GNFs (0.05 wt%GNFs) exhibiting ultimate strength of 793 MPa (+40% compared to monolithic pure Ti), have been processed by short time ball milling process followed by spark plasma sintering (SPS) and hot-rolling (HR). Enormous strength increase of the composite can be attributed to a homogeneous distribution of Ni-GNFs in the Ti matrix coupled with the formation of special interface (Ti/Ti 2 Ni/nano-TiC X /Ni-GNFs). The load transfer mechanism of Ni-GNFs in composites was investigated by in-situ tensile test, which shows the great interfacial load transfer capability. This work provides a new strategy for dispersion and interface analysis of GNFs reinforced Ti matrix composites. [ABSTRACT FROM AUTHOR]

The interfacial structure and mechanical properties of multi-layer graphene (MLG)/pure Ti composites produced by spark plasma sintering (SPS) and subsequent hot-rolling (HR) have been investigated. The hot-rolling temperature has been set at 823 K, 1023 K and 1223 K for composites to obtain various interfacial characteristics and microstructures. (Transmission electron microscopy) TEM observations reveal three types of temperature-dependent interface: Ti carbide nucleation, Ti carbide particles growth and Ti carbide layer formation. Moreover, there exists special crystallographic orientation relation: ( 1 ¯ 01) TiC //(11 2 ¯ 0) Ti and (0001) MLG //(020) TiC . Tensile test shows the MLG/Ti composite owns outstanding mechanical property. Specially, the 0.2 wt%MLG/Ti exhibits tensile strength of 1050 MPa, nearly two times higher than that of monolithic pure Ti. The relation between interfacial stress and strengthening efficiency has been investigated by using revised shear-lag mode in order to reveal the relation between interfacial microstructure and macro-mechanics. Results show that interfacial Ti carbides on partially reacted MLG led to the great improvement of interfacial strength and consequent enhancement of composites strength. When the HR temperature increased to 1023 K and 1223 K, the volume fraction of Ti carbides was 2.5 and 12.3 times higher than MLG. Ti carbide layer play a key role in further improvement of the tensile property. [ABSTRACT FROM AUTHOR]

Fe 3 Cr 2 CoNiAl x (x = 0.6, 0.7, 0.8, 1.0, 1.1, 1.2) high entropy alloys (HEAs) with dual-scales B2 precipitated were prepared. The microstructure changed from face-centered-cubic (FCC) and body-centered-cubic (BCC) to a single BCC structure with the increasing of Al content. By controlling the concentration of Al element in the BCC-based HEAs, the structure can be tuned to two coherent BCC phases: medium B2 (m-B2) precipitates with an average length of 200–300 nm and smaller size B2 (s-B2) precipitates with an average diameter of 10–50 nm. The compression tests indicated that the Fe 3 Cr 2 CoNiAl 1.2 HEA exhibited excellent compression properties, which yield strength and fracture strain is 1464 MPa and 20%, respectively. Furthermore, the strengthening mechanism has been discussed, and it is determined that the main strengthening mechanism was precipitation strengthening. This work provides a useful mean by tailoring multi-scale phase to achieve excellent properties in BCC-based high entropy alloys. • The increase of Al content promoted the structure of Fe 3 Cr 2 CoNiAl x HEAs from FCC plus BCC to BCC plus B2. • Al1.2 alloy have two types B2 phases: m-B2 (200–300 nm) and s-B2 (10–50 nm). • The yield strength and fracture strain of Fe 3 Cr 2 CoNiAl 1.2 alloy are 1464 MPa and 20% respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Crystal sheet lattices were proposed with smooth profiles and reduced anisotropy. • High mass-specific stiffness and energy absorption capability were achieved. • The strengthen mechanism was experimentally and numerically studied. Cellular materials with smooth profiles, improved structural strength, and reduced elastic-anisotropy are eternal pursuit in bone-implant filed. However, it is a huge task to meet so many requirements. In this work, a novel class of mechanical metamaterials, named as crystal sheet lattices, were proposed. The elastic performances were investigated using representative elementary volume model and examined by quasi-static compression tests. The plastic performances and energy absorption behaviors were experimentally calibrated. Meanwhile, elastoplastic simulations were adopted to study the deformation mode on the structural strengthen mechanism. The results demonstrate that the reduced elastic-anisotropy can be achieved without complicated regulation process. Under the same material volume fraction, the stiffness, yield strength, and energy absorption capability were respectively increased about 30%–60%, 30%–150%, and 70%–280%, for most of crystal sheet lattices in comparison with their truss-based counterparts. Being open type cellular materials, the crystal sheet lattices are of high mass-specific mechanical performances. Due to the smooth profiles, large surface volume ratios, and enhanced mechanical performances, CSLs also have potentials to be utilized in lightweight and heat transportation fields. [ABSTRACT FROM AUTHOR]

The objective of this study is to modulate the size of intermetallic compounds to increase the strength of Al–Ag composites. In this study, we prepared Al–Ag composites using plasma-activated sintering (PAS). The effect of the applied current on the nucleation barrier of the Al/Ag alloy phase was investigated. The strengthening mechanism of Ag-reinforced Al matrix composites was explored. We found that two alloy phases, Ag 2 Al and Ag 3 Al, were generated in the Al–Ag composites. The alloy phases distributed at the grain boundaries strengthened the Al–Ag composites by enhancing the dislocation density in the matrix and by impeding dislocation motion. The ultimate tensile strength and yield strength of the Al–7Ag composite increased by 60.1% and 166%, respectively, compared with those of pure Al. Moreover, we calculated the contribution of each strengthening mechanism to the overall yield strength. The applied current lowered the nucleation barrier of the alloy phase and facilitated the nucleation process. [ABSTRACT FROM AUTHOR]

Silica/Cu composites generally fail to achieve the high strength due to the weak interfacial bonding between SiO 2 and Cu. In the current work, the first use of silica quantum dots (SiO 2 QDs) as a copper-based composite reinforcement. Silicon quantum dots (Si QDs) and copper acetate are employed as raw materials for spray pyrolysis to obtain an interconnected structure of SiO 2 QDs/Cu 2 O, which achieve well-dispersion of the reinforcement and good interface combination in one step. The SiO 2 QDs/Cu 2 O composite block is obtained by ball milling, hydrogen reduction, and SPS sintering. Micro interface structure and strengthening mechanism of the composites are investigated and presented in detail. Microstructural analysis discovers the Cu 2 O transition layer between SiO 2 QDs and Cu matrix and well-dispersed SiO 2 QDs in the Cu matrix. The good bonding of grain interface can significantly enhance the mechanical properties. The 1.2 wt% SiO 2 QDs/Cu composite block exhibits an excellent ultimate tensile strength of 456.63 MPa, which is 101.68% higher than that of unreinforced Cu (227.39 MPa). Furthermore, the composite block maintains the high conductivity (83.27% IACS) and elongation (8.86%). Moreover, this work can promote the development of Cu matrix composites using ceramic reinforcement with an improved interface bonding. • The SiO 2 QDs as a copper-based composite reinforcement is firstly presented. • Good dispersion of the reinforcement in the matrix and strong interface combination are obtained by spray pyrolysis method. • The composite compact has achieved good mechanical properties and high conductivity. [ABSTRACT FROM AUTHOR]

• Al-Mg-Li-Sc-Zr alloy was prepared by rapid solidification and ingot metallurgy. • Rapid solidification improves the mechanical properties of Al-Mg-Li-Sc-Zr alloy. • An excellent ultimate tensile strength of 352 MPa was obtained for the HIPed alloy. • Two-stage homogeneous treatment promoted the precipitation of Al 3 (Sc Zr) dispersoids. The microstructural evolution and mechanical properties of Al-Mg-Li-Sc-Zr alloys fabricated by ingot metallurgy (IM) and gas atomization (GA) with hot isostatic pressing (HIP) were investigated. The results showed that the as-cast alloy exhibits a coarse grain microstructure with large amounts of Al 2 MgLi and primary Al 3 (Sc, Zr) particles in the matrix. While a fine and uniformly structured HIPed alloy with a relative density of 99.9% can be obtained at 400 °C for 2 h, and no primary Al 3 (Sc, Zr) phase nor macro-segregation existed in the HIPed alloy. After a two-stage homogenization treatment, the Al 3 Li, Al 2 MgLi, and AlLi phases dissolved into the matrix, and simultaneously dense Al 3 (Sc, Zr) dispersoids precipitated in the two alloys. The number fraction of the Al 3 (Sc, Zr) phase in the HIPed alloy was much higher than that in the as-cast alloy. An excellent ultimate tensile strength of 352 MPa was obtained for the HIPed alloy, an increase of approximately 14% compared with the as-cast alloy. The increased strength in the HIPed alloy is mainly attributed to grain boundaries, precipitation, and solid-solution strengthening mechanisms. [ABSTRACT FROM AUTHOR]

Discontinuously reinforced 3D network structured Ti6Al4V (TC4) matrix composites with multilayer graphene (MLG) were fabricated via 3D dynamic mixing and spark plasma sintering (SPS) at high pressures (250–500 MPa). The interface microstructure, mechanical properties and strengthening mechanisms were systematically studied with various MLG contents. Experimental results exhibited that MLG can be relative uniformly dispersed onto the surface of TC4 powders by the 3D dynamic mixing method, SPS parameter of 700 °C-500 MPa caused weak interface bonding between MLG and Ti matrix, and 900 °C-250 MPa was determined as the optimal sintering condition. Appropriate ratio of in-situ generated TiC phase with approximately 30 vol% retained MLG at the interface was beneficial to the interface bonding. The compressive strength of the composites was remarkably enhanced with excellent compressive ductility. Superior mechanical properties with the highest strengthening efficiency (65.5%) and tensile strength, acceptable tensile ductility (9.0%) and higher Vickers microhardness were achieved in the 0.15 wt% MLG composites due to its better interface microstructure. The network interface strengthening mechanism by the TiC phase and residue MLG is proposed to be the dominant mechanism with a few contributions from C solid solution and fine-grain strengthening. Unlabelled Image • High-pressure SPS combined with 3D dynamic mixing was used to fabricate graphene reinforced Ti6Al4V composite. • Reaction ratio of TiC to graphene about 7:3 at interface led to better load-bearing capacity. • Composite with 0.15 wt.% graphene addition had the highest strengthening efficiency (65.5%) and acceptable ductility (9%). • The network interface strengthening by the TiC phase and residual graphene was the dominant mechanism. [ABSTRACT FROM AUTHOR]

In order to analyze the strengthen behaviors of the Y element, the microstructures and mechanical properties of Mg-10Gd-0.2Zn- x Y-0.4Zr (x = 0, 1 wt%) two alloys were investigated. Based on the experimental results, Y addition could largely refine the size of β′ precipitate and increase its number density. This phenomenon has been analyzed by theoretical studies in this paper. Due to the fine and dense β′ precipitates, the mechanical properties of the Y-containing alloy was highly improved. In addition, β 1 precipitate also has important contribution to the mechanical property. Based on the TEM observation, after tensile test, the β′ precipitates were obviously sheared by the 11 2 ¯ 0 α slip dislocations in Y-containing and Y-free alloy, then, it illustrates that the strengthen effect in both two alloys was mainly derived from the shearable mechanism. [ABSTRACT FROM AUTHOR]