Construction of dual heterogeneous interface between zigzag-like Mo–MXene nanofibers and small CoNi@NC nanoparticles for electromagnetic wave absorption

Two-dimensional(2D)transition metal carbides(MXene)possess attractive conductivity and abundant surface functional groups,providing immense potential in the field of electromagnetic wave(EMW)absorption.However,high conductivity and spontaneous aggregation of MXene suffer from limited EMW response.Inspired by dielectric–magnetic synergy effect,the strategy of decorating MXene with magnetic elements is expected to solve this challenge.In this work,zigzag-like Mo_(2)TiC_(2)–MXene nanofibers(Mo-based MXene(Mo–MXene)NFs)with cross-linked networks are fabricated by hydrofluoric acid(HF)etching and potassium hydroxide(KOH)shearing processes.Subsequently,Co-metal–organic framework(MOF)and derived CoNi layered double hydroxide(LDH)ultrathin nanosheets are grown inside Mo–MXene NFs,and the N-doped carbon matrix anchored by CoNi alloy nanoparticles formed by pyrolysis is firmly embedded in the Mo–MXene NFs network.Benefiting from synergistic effect of highly dispersed small CoNi alloy nanoparticles,a three-dimensional(3D)conductive network assembled by zigzag-like Mo–MXene NFs,numerous N-doped hollow carbon vesicles,and abundant dual heterogeneous interface,the designed Mo–MXene/CoNi–NC heterostructure provides robust EMW absorption ability with a reflection loss(RL)value of−68.45 dB at the thickness(d)of 4.38 mm.The robust EMW absorption performance can be attributed to excellent dielectric loss,magnetic loss,impedance matching(Z),and multiple scattering and reflection triggered by the unique 3D network structure.This work puts up great potential in developing advanced MXene-based EMW absorption devices.

Superb strength and ductility balance of a Co-free medium-entropy alloy with dual heterogeneous structures

In present work,we successfully fabricated a novel Co-free non-equiatomic Ni_(46)Cr_(23)Fe_(23)Al_(4)Ti_(4)mediumentropy alloy with dual heterogeneous structures,i.e.three-levels grain structures and heterogeneous L1;precipitates.Experimental results revealed the dual heterogeneous structures lead to remarkable strength-ductility synergy properties in this Co-free medium-entropy alloy,showing high yield strength and ultimate tensile strength of~1203 MPa and~1633 MPa,respectively,remaining an excellent ductility of~28.7%.Further analyses about strengthening and deformation mechanisms indicated precipitation hardening and hetero-deformation induced hardening contribute the majority strength enhancement,meanwhile deformation-induced hierarchical stacking-faults networks,high density Lomer-Cottrell locks and microstructure features of heterogeneous grains and precipitates substantially facilitate the high work-hardening capacity and excellent tensile ductility.This work not only offers fundamental understanding of the strength and deformation mechanisms of the dual heterogeneous structural material,but also provides useful strength design strategy for low-price high performance high/medium-entropy alloys.