Unveiling heterogeneous microstructure and good combinations of high yield strength and low coercivity of in-situ formed NbC/FeNiCo medium-entropy composites

• Published in: Powder technology 2023-04, Vol.419, p.118365, Article 118365
• Main Authors: Chu, Chenliang, Chen, Weiping, Fu, Zhiqiang, Wang, Hao, Jiang, Zhenfei, Xiong, Wei, Chen, Qiang
• Format: Article
• Language: English
• Subjects: Heterogeneous structures; Mechanical properties; Medium-entropy composites (MECs); Soft-magnetic properties; Spark plasma sintering (SPS)
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2023.118365

It is very challenging to achieve exceptional combinations of soft-magnetic and mechanical properties in conventional soft-magnetic alloys. To tailor combinations of soft-magnetic and mechanical properties, different volume fractions of in-situ formed NbC were designedly introduced into the recently emerged equi-atomic FeNiCo medium-entropy alloy displaying appealing soft-magnetic properties but disappointing strength. The bulk NbC/FeNiCo medium-entropy composite (MEC) with ∼7.8 vol% NbC (MEC7.5) consisted of ultra-fine and fine FCC grains with nano-sized NbC, realized the best combinations of mechanical and soft-magnetic properties. In detail, it showed an ultra-high tensile yield strength of ∼1158 MPa and an improved elongation of ∼4.6%, resulting from dislocation strengthening, dispersion strengthening and hetero-deformation induced strengthening. Simultaneously, the saturation magnetization and coercivity of the MEC7.5 were ∼ 143 emu/g and ∼ 382 A/m, suggesting that it has good soft-magnetic properties. Therefore, our findings provide a new paradigm for realizing outstanding combinations of high yield strength and low coercivity in alloys. [Display omitted] •Mechanical and soft-magnetic properties of equiatomic FeCoNi were tailored by NbC.•In-situ NbC favored forming heterogeneous structures in NbC/FeCoNi composites.•7.8 vol% NbC had the best combinations of mechanical and soft-magnetic properties.•Heterogeneous structures were primarily responsible for the appealing properties.