In situ FeCrB whiskers and TiB particles strengthened Fe1.2MnNi0.8Cr matrix composites

Highlights: • The FeCrB_w and TiB_p reinforcements were formed in situ in Fe_1.2MnNi_0.8CrTi_xB_2x matrix composites. • The hardness, YS and UTS reached the highest values in S₂, which are 678 Hv, 639 MPa and 924 MPa, respectively. • Strengthening mechanisms are mainly dislocation interactions. Combining the distinct design advantages of composite materials and high entropy alloys (HEA), novel Fe_1.2MnNi_0.8CrTi_xB_2x (x = 0, 0.1 and 0.2) alloys with high strengths were synthesized and investigated for load-bearing application. FeCrB whiskers (FeCrB_w) and TiB particles (TiB_p) were found forming in situ in the alloys. Among the alloy composites Fe_1.2MnNi_0.8CrTi_0.2B_0.4 was found to possess the highest values in the yield strength (YS) and ultimate tensile strength (UTS), which are 639 MPa and 924 MPa, respectively, representing an increase by 58% and 40% as compared to the Fe_1.2MnNi_0.8Cr matrix. The uniform elongation remains to be fair for this new alloy. The enhanced strength for the composites is attributed to the formation of TiB_p and FeCrB_w, which effectively hindered the dislocation motion. However, the rigid interfacial bonding between the whiskers and the alloy matrix, as well as random distribution of FeCrB_w, impaired the ductility to the composites.