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In this study, B4C/6061Al nanocomposites reinforced with various volume fractions of nano‐sized B4C particles (B4C/6061Al NCs) are successfully fabricated by a powder metallurgy route consisting of spark plasma sintering (SPS) and hot extrusion and rolling (HER). The microstructure evolution, phase composition, and mechanical properties of B4C/6061Al NCs are experimentally investigate. The results show that nearly fully dense (maximum ≈99.21%) as‐SPSed NCs can be fabricated, and this can be attributed to joule heating at the particle contacts and tip spark plasma at the gaps. Nanosized B4C particles mainly distributed in the 6061Al particles boundaries and formed inhomogeneous network materials in as‐SPSed NCs, while B4C particles distributed relatively homogeneously in the 6061Al matrix after HER. No new phases are found in the B4C/6061Al NCs over three deformation stages. The pin effect of the nanosized B4C can suppress dynamic recovery and improve the driving force for dynamic recrystallization. The mechanical properties are further improved after HER, and the maximum ultimate tensile strength and yield strength for as‐rolled NCs are 305 and 168 MPa. The strengthening mechanisms mainly included load transfer strengthening, dislocation strengthening, Orowan strengthening, and fine‐grain strengthening. [ABSTRACT FROM AUTHOR]

With the advantage of micro-size and nano-size B 4 C particles, micro-/nano-bimodal size B 4 C particles have been widely used to fabricate excellent composites with high strength and ductility. In this study, micro-/nano-bimodal size B 4 C particles reinforced aluminum matrix composites with three different volume fractions (3%, 5% and 7%) were fabricated by spark plasma sintering (SPS) followed by hot extrusion and rolling (HER). The microstructure evolution and mechanical properties of as-SPSed, as-extruded and as-rolled composites were investigated. Results show that the microscopic electrical discharge between the particles in SPS promotes the densification of composites. The maximum relative density of as-SPSed composites increases from 99.21% to 99.65% after HER. Nano-size B 4 C particles distribute mainly at the gap of 6061Al particles in as-SPSed composites, while the microstructure presents more homogeneous after HER. Pin effect of nano-size B 4 C particles stimulates dynamic recrystallization (DRX) and grain refining. Texture orientation of the 6061Al grain exists in the as-extruded and as-rolled B 4 C/6061Al NCs. No new phases are detected in composites in all deformation stages. The tensile strength of as-SPSed composites increases when compared with 6061Al matrix, and the tensile strength of as-rolled composites after hot extrusion is enhanced to 305 MPa. Fracture mechanisms of as-extruded and as-rolled composites mainly include 6061Al matrix tear, particle/matrix interfacial tear and micro-size B 4 C particle fracture. [ABSTRACT FROM AUTHOR]

In this paper, both experimental and theoretical studies were conducted to investigate the bonding interface formation, microstructure evolution, and the interface strength of an AA6061/AZ31B alloy cladding plate fabricated by explosive welding. The evolution of microstructures including adiabatic shear bands (ASBs) structure, recrystallized grains, and elongated grains were analyzed using optical microscope (OM), electron back scatter diffraction (EBSD), and transmission electron microscope (TEM). A model was also proposed to study the ASBs formation and recrystallized grains in the ASBs. In the study, during explosive welding, a periodic wavy bonding interface was observed and the formation of such an interface was found due to the periodic jetting caused by the high impact stresses at the impact points during welding. The ASBs were found formed along the directions where the stress waves were concentrated due to high energy accumulation. Near the bonding interface, many crystallized grains were found in the AZ31B alloy plate, while elongated grains were dominant in the AA6061 alloy plate. Difference in the crystal structure of the Al and Mg alloy was believed to be the reason causing such microstructure evolution difference. Nanoindentation tests on the ASBs showed that, due to the existence of fine grains resulted from the recrystallization in the ASBs structure, the hardness of the ASBs structure (1.22 GPa) was higher than that of its surrounding structure. The shear strength of the bonding interface of the explosively-welded AA6061/AZ31B cladding plate can reach up to 201.2 MPa. [ABSTRACT FROM AUTHOR]

In this paper, a novel approach to evaluate the neutron shielding performance of a boron-containing neutron absorbing material was proposed for the first time through the establishment of a direct relationship between 10 B areal density ( 10 BAD) of the material and its neutron absorption ratio. It is found when the 10 BAD of a material is greater than 0.034 g/cm 2 , the material will achieve a good neutron shielding performance. Based on this proposed approach, B 4 C/6061Al composite plates with different B 4 C content (10 wt%, 20 wt%, 30 wt%) were successfully fabricated using vacuum hot pressing followed by hot-extrusion. The characteristics of the B 4 C/Al interface were studied in details using transmission electron microscopy (TEM), and the effects of B 4 C particle content on microstructure and mechanical properties of the Al matrix were investigated. Through current studies, B 4 C/6061Al composite plates possessing good neutron shielding performance and tensile strength are found to be able to be fabricated using either 20 wt% of B 4 C content with a plate thickness of 4.5 mm or 30 wt% B 4 C content with a plate thickness of 3 mm. [ABSTRACT FROM AUTHOR]

This paper presented a new type of neutron absorption material used in the storage and transportation of spent fuel in nuclear power plants as SiC/Gd 2 O 3 /6061Al composites (SGAC). The optimal component proportion of composites was designed by neutron shielding simulation with MCNP5 software and mechanical property simulation with LAMMPS software. The influence of SiC content on the neutron shielding performance and mechanical properties of the composites was explored by numerical simulation. SGAC with different content of SiC were prepared by SPS technology. The thermal neutron shielding properties, microstructure and mechanical properties for SGAC were analyzed by neutron shielding tests, XRD, typical SEM, TEM, and tensile tests. The neutron shielding test shows that the neutron shielding performance of (0 wt%-25 wt%) SiC/5 wt% Gd 2 O 3 /6061Al SGAC with a thickness of 5 mm all reach above 99.5%. Nanometer Gd 2 O 3 particles and micron SiC particles play intragranular and intergranular reinforcement effects on Al matrix respectively. A new phase Al 4 SiC 4 is generated at the interface of the two phases, facilitating the connection of interfaces. (15 wt% SiC+5 wt% Gd 2 O 3)/6061Al shows superior mechanical properties with the tensile strength of 196 MPa and the elongation of 11%. [ABSTRACT FROM AUTHOR]

The AlCoCrFeNi 2.1 eutectic high-entropy alloys (EHEAs) were prepared by selective laser melting (SLM) with powders of different particle sizes as variables. The spreading process of powders with different particle sizes and the effect of particle size on densification behavior, phase and mechanical properties were studied. The maximum densification of the D 50 16 sample is 99.58%, while that of D 50 35.8 is 99.1%. For the D 50 16 system, the BCC/B2 phase of the powder is transformed into the FCC phase of the SLM product, while the reverse is true for the D 50 35.8. The microhardness of SLM-printed coarse powder samples is higher than that of fine powder by more than 100 HV, and the microhardness of X-Y plane is about 20–40 HV higher than that of X-Z plane. The compressive strength and plasticity of the D 50 16 sample are 300 MPa, 8% (⊥BD) and 60 MPa, 9% (∥BD) higher than that of D 50 35.8. [Display omitted] • The Max densification of the D 50 16 powder SLM sample is 99.58%. • The columnar and equiaxed crystals are formed in the SLM melt pool. • SLM coarse powder samples have higher microhardness than fine powder samples. • SLM D 50 16 sample has better compression properties than that of D 50 35.8 sample. • The laser absorption rate of D 50 16 powder is 3.6% higher than that of D 50 35.8 powder. [ABSTRACT FROM AUTHOR]

Invar 36 samples were fabricated via laser powder bed fusion (LPBF) at various energy densities. In this work, a parameter range for the preparation of full-density Invar 36 samples was determined. The microstructural evolution and tensile properties of the materials were studied in the as-LPBFed state, and the role of subgrain structures on the fracture mechanism was investigated. According to the results of this analysis, as the energy density increased, the density first increased and then decreased. The maximum density (99.94 %) reached 65 J/mm3, and the simple density reached full density at 40–90 J/mm3. Due to constitutional supercooling, the microstructure of the alloy is composed of cellular subgrains and columnar subgrains. Columnar subgrains grow perpendicular to the boundary of the molten pool to the center of the molten pool, while cellular subgrains primarily exist in the remelting area of the molten pool. In the full density range, the ultimate tensile strength of the samples reaches 437–484 MPa, and differences in the morphology, distribution, and micronicomechanical properties of the subgrains are responsible for the differences in macroscopic properties. At 40, 65, and 90 J/mm3, the elastic moduli of the columnar subgrains are approximately 155.1 GPa, 161 GPa, and 162.4 GPa, respectively; the elastic moduli of the cellular subgrains are approximately 136.2 GPa, 140.2 GPa, and 139.9 GPa, respectively, which means that in the elastic deformation stage, the columnar subgrains are more resistant to elastic deformation; in the plastic deformation stage, different subgrains have different effects on crack propagation; the columnar subgrains grow perpendicularly to the melt pool boundary, which has a hindering effect on the extension of microcracks; and the cellular subgrains have a homogeneous grain size so that the microcracks can be easily extended along the cellular subgrain boundaries. • Evolution of subgrains microstructure of LPBF-prepared Invar alloys. • Verification of micro-nano mechanical properties of different subgrains microstructure and investigation of the reasons for performance differences. • Further reveals the failure forms of different subgrains and the transformation of subgrains failure forms with the change of energy density. • The relations between mechanical properties and subgrains characteristics are established. [ABSTRACT FROM AUTHOR]

In this study, the neutron shielding and mechanical properties of short carbon fiber reinforced aluminium 6061-boron carbide hybrid composite have been investigated by simulation and experimental methods. The simulation results indicated that in the energy range of the epithermal neutrons which have greater kinetic energy than thermal neutrons (0.0253ev), the introduction of fiber materials containing carbon atoms into aluminium 6061-boron carbide increases the probability of neutron scattering, meanwhile the epithermal neutrons slowed down by the carbon atoms, hence the shielding performance will be improved. Additionally, compared with aluminium 6061-boron carbide composite, it was found that the short carbon fiber reinforced hybrid composite has better strengthening effect on matrix, mechanical tests show the enhancement in tensile strength and hardness. Moreover, the short carbon fiber can hinder crack propagation and absorb fracture work during the stress process while enhance the toughness of the neutron shielding composite. [ABSTRACT FROM AUTHOR]

In this study we investigated the effect of multi-pass rolling and post-rolling heat treatment upon the microstructure at interface and mechanical properties of the explosive welding Mg/Al composite plates. The thin explosive welding Mg/Al composite plates with 2.14 mm in thickness and good surface quality were obtained by 5 passes hot rolling (30% reduction, 400 °C). To meet the requirement of subsequent forming, annealing process was performed. The results indicate that the thickness of interfacial diffusion layer increases with the increase of annealing temperature and holding time. The mechanical properties of composite plates increase first and then decrease with the increase of annealing temperature and holding time. The tensile strength and elongation of the composite plates under 200 °C/2 h annealing condition reach the maximum, which are 285 MPa and 24.5% respectively. Fracture surface morphology indicates that the post-rolling or annealed composite plates all exhibit mixed-mode of ductile and brittle fractures. [ABSTRACT FROM AUTHOR]

• Investigated the influence of quenching temperature on the tensile fracture behavior of FeCrAl. • Obtained the heat treatment process that can effectively control the homogeneity of the structure. • Explained the coordination mechanism of the microstructure recovery process on the strength plasticity of FeCrAl alloy. • Control the uniformity of the structure to ensure the strength property and increase the plasticity by 50% The effect of quenching treatment on the structure and tensile properties of FeCrAl rolled-state alloy was systematically investigated to optimize its strength-ductility trade-off. After quenching at 960 °C for 400 s, the inhomogeneous weave gradient consisting of equiaxed and columnar grains in the rolled plate was transformed into uniform equiaxed grains, while the elongation rate of the FeCrAl alloy reached 24 % from 16 %, a large number of ductile dimples appeared in the tensile fracture, as well as a 50 % improvement in ductility. This work highlights the potential of FeCrAl alloys to reach the recovery stage at the heat treatment limit and improve the structure homogeneity to obtain optimized mechanical properties. This study can provide theoretical guidance for the industrial production of the FeCrAl alloy. [ABSTRACT FROM AUTHOR]

The addition of boron to long-periodic stacking ordered (LPSO) phase-strengthened Mg–Zn–Y system alloys has been studied for the first time. The as-cast Mg 94 Zn 2.5 Y 2.5 Mn 1 alloy containing 0.003 wt% B with abundant LPSO phase and refined grains exhibited optimal mechanical performance with ultimate tensile strength and elongation of 252.5 MPa and 11.0%, respectively. [ABSTRACT FROM AUTHOR]

• Shielding properties for neutron and gamma-radiation obtained by MCNP5 simulation. • Core-shell Gd 2 O 3 @W particles prepared through ball milling. • Double strengthening effect of core-shell Gd 2 O 3 @W particles. • Crack growth at the interface between core-shell particles and matrix. Particles of micron gadolinium oxide core and nano tungsten shell were introduced into aluminum matrix to prepare neutron and gamma ray co shielding materials. The neutron and gamma ray simulation results show that the absorption efficiency for neutron and the half value layers for primary and secondary gamma ray meet the shielding application. Morphology of core-shell structures and composites have been analyzed using scanning electron microscopy. Compared with the original particles reinforced aluminum matrix composite, tensile strength is improved by the core-shell structure particles. The tensile fracture morphology shows that the main reason for the transgranular fracture of composite is that the grain boundary Gd 2 O 3 @W particles prevent the crack growth. [ABSTRACT FROM AUTHOR]

In the present work, 5083Al matrix composites reinforced by 10 vol% AlCoCrFeNi high-entropy alloy (HEA) particles were fabricated by submerged friction stir processing (SFSP). It was found that the fabricated composites consist of equiaxed fine grains with the mean size of 1.2 μm due to dynamic recrystallization, particle stimulated nucleation (PSN) and shortened thermal cycle by water cooling. The HEA/5083Al interface showed a two-layer structure, the layer close to the HEA exhibited FCC + T phases with the thickness of approximately100 nm, and the other layer consisted of the Cr-depleted AlCoCrFeNi HEA particles in the size of roughly 100 nm. The SFSPed HEA/5083Al composites showed 25.1% higher yield stress (YS) and 31.9% higher ultimate tensile strength (UTS) in comparison with the base metal while maintaining acceptable ductility (18.9%). Grain refinement, geometrically necessary dislocations and load transfer effect can mainly be responsible for the improved strength. • SFSP were conducted on AlCoCrFeNi high entropy particles reinforced aluminum matrix composites. • CDRX, PSN and shortened thermal cycle by water cooling can be responsible for the grain refinement. • The interface structure was characterized to investigate the interface formation mechanism. [ABSTRACT FROM AUTHOR]