Search

Novel HEAp-Ti/Al laminated composites embedded with particles of the high-entropy alloy Al0.5CoCrFeNi (HEA) were fabricated by vacuum hot-press sintering at 730 °C. The phase composition and microstructure of the composites were studied with X-ray diffractometer (XRD), scanning electron microscope SEM, energy dispersive spectrometer (EDS), transmission electron microscope (TEM), and electron backscattering diffraction (EBSD) techniques. At this temperature, it has been observed that Al3Ti intermetallic compound is the favored phase and the reaction results in the dispersion of Al3Ti in the original Al layer. A large number of interfaces are formed between Al3Ti and Al. The deformed Al3Ti grains are concentrated in the interface near the Ti side. The mechanical properties, including tensile and compressive properties at room temperature, were analyzed. The tensile test results indicate that the composite exhibited an average tensile strength of 258 MPa and an average yield strain of 9.86%. Compression test results show that when a load perpendicular to the layer is applied, the yield strain and yield stress of the material are 9.67% and 474.09 MPa, respectively. Moreover, under a load parallel to the layer, the material fails due to interfacial debonding. [ABSTRACT FROM AUTHOR]

Serration behavior is a kind of plastic instability phenomenon of materials, which widely exists in the high-entropy alloys and has influence on microstructure and mechanical properties. In this work, the microstructure and mechanical properties of a NiCrFeCoMn high-entropy alloy (HEA) were studied under high-speed impact. The microstructure of a NiCrFeCoMn HEA were investigated by optical microscope (OM), scanning electron microscope (SEM), electron backscatter diffraction (EBSD), and transmission electron microscope (TEM). The dislocation density increased with the true strain at high-strain-rate deformation, and the dislocations can be hindered and released continually by the twin layers, resulting in serration on the true stress—true strain curve. When values of the strain rates are 1250, 2000 and 4800 s−1, the yield strength of the deformed NiCrFeCoMn HEA are 510, 525 and 680 MPa, respectively. Moreover, the fluctuation of the serration became more serious with the increasing of the strain rate. Compared with the as-cast NiCrFeCoMn HEA, the true stress—true strain curve of the deformed NiCrFeCoMn HEAwas smoother. [ABSTRACT FROM AUTHOR]