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A novel method of preparing continuous NiTif‐reinforced Ti/Al‐laminated composites is proposed via ultrasonic consolidation (UC) and vacuum hot pressing. The microstructure of the composites is characterized by X‐ray diffraction, scanning electron microscopy, and electron backscattering diffraction. The tensile properties of the composites are measured by a universal testing machine. Results indicate that the composite exhibits multilayer structure consisting of residual NiTi fiber, intermetallic compounds (IMCs) layer, reaction layer, Ti layer, and Al layer. The intermetallic layer is composed of Al3Ti and Al3Ni, and some Ni‐rich precipitates are dispersed in the matrix. And with the introduction of UC assisted, grain refinement occurs at the IMC/Al interface, texture variation emerges at the NiTi fiber/IMCs interface, and a weakening of texture strength is observed at both interfaces. Compared to NiTif‐reinforced Ti/Al‐laminated composites without UC assisted, both the tensile strength (from 872.4 to 826.5 MPa) and failure strain (from 17.5% to 20.4%) of NiTif‐reinforced Ti/Al‐laminated composites with UC assisted increase due to the contribution of UC assisted. The reinforcing and fracture mechanisms of the UC assisted are also discussed. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) usually leads to the epitaxial growth of columnar grains in the deposition layer along the construction direction, typically resulting in the decrease in mechanical properties. In this study, A517Q alloy steel was fabricated by laser and wire additive manufacturing (LWAM) assisted with ultrasonic vibration (UV) treatment. The microstructure characteristics of A517Q alloy steel under different UV affected were investigated by OM, XRD, SEM, and EBSD. Compared with the sample without UV, the percentage of equiaxed grains in samples with dual UV increased by 90%. Due to the optimization of grain structure, the tensile strength of the sample with dual UV increased by 29% and the elongation had also been improved. The results showed that due to the cavitation and acoustic flow effects of ultrasonic, the temperature gradient (G) of the molten pool reduced and the solidification rate (R) increased, thus promoting the transformation from columnar grains to equiaxed grains. [ABSTRACT FROM AUTHOR]

Aluminum matrix composites (AMCs) reinforced by 5 wt% B4C particles were fabricated by direct laser deposition (DLD) technology. The phase composition, microstructure, and microhardness of the B4C/aluminum matrix composites (B4C/AMCs) were analyzed by OM, XRD, SEM, TEM, EBSD, microhardness test and molecular dynamics simulation (MD) in detail. The results show that acicular microstructure of AlB12 and Al4C3 are formed in the B4C/AMCs fabricated by DLD. With the addition of B4C, the crystallographic orientation of AMCs changes from (001) texture to random orientation distribution, and the microhardness increases by about 65%. During the DLD process, boron atoms and carbon atoms are released by B4C decomposition instead of diffusing through the solid–liquid interface between Al and B4C, and they react with the liquid Al to produce AlB12 and Al4C3 in the molten pool. Moreover, B and C atoms distribute along a strip orientation in the molten pool, which may be retained after the cooling to form the acicular microstructures. This work demonstrates the possibility and good prospects of obtaining AMCs reinforced with B4C, AlB12 and Al4C3 phases by the DLD technique and provides new insights into the microstructural evolution of the composites. [ABSTRACT FROM AUTHOR]