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TiC/Fe 0.6 MnNi 1.4 medium entropy alloy matrix composites with different volume fractions of TiC particles (i.e., 5, 10 and 15 vol%) were prepared by induction melting method. The experimental results showed that both the base alloy and the composite matrix possess face-centered cubic structure. The in-situ TiC reinforcement phase can significantly increase the mechanical properties of the composites at room temperature. In particular, the hardness, yield strength and ultimate tensile strength of the 10 vol%TiC/Fe 0.6 MnNi 1.4 composite are found respectively to be 528 HV, 345.1 MPa and 716.7 MPa, representing a marked increase by 51.7%, 41.1% and 30.7% in comparison with the Fe 0.6 MnNi 1.4 medium entropy alloy. The ductility of the composite in terms of the elongation to failure is reduced from 65.8% to 36.6% with the increase of the TiC content, which remains attractive for load-bearing structural applications. The strength improvement is underpinned by a combination of the load-bearing effect, Orowan process, dislocation interactions and solid solution effect. [ABSTRACT FROM AUTHOR]

High entropy alloys (HEAs) have recently aroused wide attention due to the outstanding mechanical properties. In this study, the in-situ TiC particles were introduced to CoCr 3 Fe 5 Ni HEA via vacuum induction smelting. Compared to the CoCr 3 Fe 5 Ni matrix, the addition of 10 vol% TiC significantly enhances the mechanical properties of composite, resulting in a hardness increase of 22.9 %, yield strength increase of 30.5 % and ultimate strength increase of 23.0 %, reaching values of 358.0 HV, 401.3 MPa and 795.4 MPa, respectively. Although the elongation of the composite is sacrificed, the value of 17 % is still acceptable. It is revealed that through the incorporation of in-situ TiC particles, multiple strengthening mechanisms including load-bearing effect, dislocation strengthening and solid-solution strengthening contribute to boosting its mechanical properties. [Display omitted] • TiC particles changed the structure of the HEA from FCC + BCC to FCC + TiC. • 2. 10 % TiC/CoCr 3 Fe 5 Ni presented an excellent combination of strength and ductility. • The enhancement of strength is attributed to multiple strengthening mechanisms. [ABSTRACT FROM AUTHOR]

Here, judicious heat treatment is used to enhance the mechanical properties of 5 vol%TiC/Fe 0.6 MnNi 1.4 composites. After annealing at 1100 °C, M 23 C 6 (M = Fe, Mn, Ni) precipitates formed, imparting the composites remarkable mechanical properties, with the ultimate tensile strength and ductility determined to be 805.5 MPa and 51.1%, respectively. • TiC/Fe 0.6 MnNi 1.4 composites were annealed, in which fine M 23 C 6 precipitates formed. • M 23 C 6 precipitates played a decisive role in microstructural refinement and property enhancement. • Annealing at 1100 °C yielded an optimal combination of the strength and ductility in the composites. [ABSTRACT FROM AUTHOR]

In-situ TiC particulate reinforced CrMnFeCoNi 0.8 high entropy alloy (HEA) matrix composites were prepared by induction melting method. The effect of TiC content upon the microstructure and tensile properties of as-cast samples were analyzed and discussed. The HEA matrix has single-phase face-centered cubic (FCC) structure, determined by X-ray diffraction (XRD) pattern. Compared to the CrMnFeCoNi 0.8 matrix, 7.5 vol%TiC/CrMnFeCoNi 0.8 composite possessed remarkable yield strength (517.1 MPa vs 240.9 MPa), ultimate tensile strength (926.2 MPa vs 527.5 MPa) and excellent uniform elongation (38.0%). Strong dislocation interactions, load-bearing effect and Orowan mechanism afforded by in-situ TiC particles, together with solid-solution strengthening via C and Ti elements, are responsible for the strength enhancement. • TiC/CrMnFeCoNi 0.8 composites were synthesized by vacuum induction melting. • In-situ TiC/CrMnFeCoNi 0.8 composites has a FCC base reinforced with TiC particles. • 7.5% TiC/CrMnFeCoNi 0.8 achieved the combination of tensile strength and ductility. • Dislocations, load bearing and Solid-solution are key strengthening factors. [ABSTRACT FROM AUTHOR]

The combined effects of vanadium additions and in-situ TiC particle formation upon the microstructure and mechanical properties of FeCrNiCu high entropy alloys were investigated. The addition of V changed the FeCrNiCu matrix structure from FCC (i.e., face-centered cubic) to FCC+BCC (i.e., body-centered cubic). The as-cast 10 vol.%TiC/FeCrNiCuV 0.1 high entropy alloy matrix composite showed excellent mechanical properties, with the yield strength and ultimate tensile strength determined to be 653.5 MPa and 1006.5 MPa, respectively. The extra strength generated by V addition and in-situ TiC particles in FeCrNiCu was evaluated, and the theoretical predictions match the experimental results well. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• The NbTiC 2 /FeCrNiCu composite contains a single FCC phase and NbTiC 2 particles. • NbTiC 2 additions can enhance the tensile strength of the alloy up to 1148.8 MPa. • Dislocation strengthening accounts for 89.6% of the strength increase. The high entropy alloy matrix composite FeCrNiCu on the basis of the face-centerd cubic structure and reinforced with 5 vol% NbTiC 2 particles was synthesized by vacuum induction melting. NbTiC 2 particles are found to be densely distributed on the substrate in polygonal shapes. The tensile strength of the NbTiC 2 /FeCrNiCu high entropy alloy matrix increased phenomenally, from 517.5 MPa to 1148.8 MPa. Though the ductility of composite is lower than the matrix, but it still presents an acceptable value of 7.1%. It is found that dislocation strengthening, loading bearing effect and Orowan mechanism are positive for enhancing the tensile properties of the high entropy alloy. [ABSTRACT FROM AUTHOR]

A series of NbC/FeCrNiCu high entropy alloy matrix composites (2.5, 5, 7.5 and 10 vol% of NbC) were prepared by vacuum induction melting. The microstructures and mechanical properties of the composites were investigated using X-ray electron diffraction, scanning electron microscopy, transmission electron microscopy, tensile and hardness tests. The results show that the FeCrNiCu high entropy alloy matrix composites are composed of FCC solid solution embedded with NbC particles. A coherent relationship was identified between the alloy matrix and reinforcement phase. The formation of NbC particles increases the hardness from 337.6 HV to 591.3 HV. Moreover, compared with the base alloy, the tensile yield strength, ultimate tensile strength and ductility of the new composite first increases and then decreases with the increase of NbC content. The tensile yield strength, ultimate tensile strength and ductility reaches maximum for the composites containing 5 vol% of NbC, which is 458.2 MPa, 691.6 MPa and 24.7%, respectively. The strengthening mechanisms of the composites are discussed and the contributions of dislocation strengthening, load bearing effect and Orowan mechanism are quantified. • The in-situ NbC/FeCrNiCu composites has a FCC base reinforced with NbC particles. • A distinct coherency exists between the alloy matrix and NbC particles. • For 5 vol% of NbC, the tensile strength and ductility increase simultaneously. • Dislocations, load bearing and Orowan mechanism are key strengthening factors. [ABSTRACT FROM AUTHOR]

• The in-situ TiC/FeCrNiCuV 0.1 high entropy alloy matrix composite has a single FCC phase structure and TiC particles. • The TiC/FeCrNiCuV 0.1 composite has a tensile strength of 1006.5 MPa and ductility of 15.6%. • Solid solution strengthening and grain size refinement have significant strengthening effect. It remains a challenge to enhance strength without sacrificing ductility for high entropy alloys. Here, we prepared in-situ TiC/FeCrNiCuV 0.1 high entropy alloy matrix composites using vacuum induction smelting. The new composites exhibit an excellent combination of high tensile strength (1006.5 MPa) and good ductility (15.6%). The improved mechanical properties, as compared to the V-free composites, are attributed to a synergy of solid solution strengthening and grain size refinement. [ABSTRACT FROM AUTHOR]