Heterogeneous lattice strain strengthening in severely distorted crystalline solids

Abstract

Multi–principal element alloys (MPEAs) exhibit outstanding mechanical properties because the core effect of severe atomic lattice distortion is distinctly different from that of traditional alloys. However, at the mesoscopic scale the underlying physics for the abundant dislocation activities responsible for strength-ductility synergy has not been uncovered. While the Eshelby mean-field approaches become insufficient to tackle yielding and plasticity in severely distorted crystalline solids, here we develop a three-dimensional discrete dislocation dynamics simulation approach by taking into account the experimentally measured lattice strain field from a model FeCoCrNiMn MPEA to explore the heterogeneous strain-induced strengthening mechanisms. Our results reveal that the heterogeneous lattice strain causes unusual dislocation behaviors (i.e., multiple kinks/jogs and bidirectional cross slips), resulting in the strengthening mechanisms that underpin the strength-ductility synergy. The outcome of our research sheds important insights into the design of strong yet ductile distorted crystalline solids, such as high-entropy alloys and high-entropy ceramics.

Quenching-Induced Defect-Rich Platinum/Metal Oxide Catalysts Promote Catalytic Oxidation

“…To show the dislocation clearly, the inverse fast Fourier transform (IFFT) of Figure h is shown in Figure S5. These dislocations were introduced during the quenching process and the existence of these dislocations would create considerable lattice strain and other defects . In order to study the surface defects further, the intensity of line-scan profiles on Pt/Fe 2 O 3 -Q was recorded and the defects in α-Fe 2 O 3 were present on the edges and flatter surfaces of the quenched samples (Figure S6a–d).…”

“…These dislocations were introduced during the quenching process and the existence of these dislocations would create considerable lattice strain and other defects. 19 In order to study the surface defects further, the intensity of line-scan profiles on Pt/Fe 2 O 3 -Q was recorded and the defects in α-Fe Raman spectroscopy was employed to examine the structure of catalysts (Figure S8). In the magnified spectrum of Pt/Fe 2 O 3 -Q shown in Figure 2a, the characteristic Raman peaks for α-Fe 2 O 3 were broadened and red-shifted compared with those of Pt/Fe 2 O 3 -S, implying the generation of abundant lattice defects induced by the quenching method.…”

Effect of Si on Microstructure and Mechanical Properties of FeCrNi Medium Entropy Alloys

“…It can be found the yield strength and elongation increase from 167 MPa and 36.2% of the Si 0 MEA to 245.9 MPa and 48.4% of the Si 0.2 MEA, respectively. This synergistic improvement of strength and ductility is mainly due to the fact that the dissolved Si atoms in the matrix can not only reduce the SFE of the MEA matrix [ 21 , 22 ], helping to induce more deformation mechanisms to enhance plasticity but also improve the strength of the MEA by causing a significant solid solution strengthening effect [ 3 , 25 ]. Figure 3 b–e shows the fracture morphologies of the as-cast Si x MEAs.…”

“…Medium/high entropy alloys (MEAs/HEAs) are expected to be candidates for structural materials in automotive, aerospace, and vessels due to their unique microstructure and outstanding mechanical properties [ 1 , 2 , 3 ]. MEAs/HEAs with single-phase face-centered cubic (FCC) and body-centered cubic (BCC) structures are the most widely studied so far [ 4 , 5 , 6 ].…”

Microstructural Understanding of Hydroxyapatite Addition on Age Hardening, Internal Friction, and Mechanical and Electrochemical Response of Resorbable Magnesium Alloys with Good Cytocompatibility

“…A similar lattice strain-induced strengthening has been reported to exhibit mechanical property enhancements in other systems. 47,48 The variation of stress−strain in the microstrain range (one complete cycle of loading and unloading) obtained using DMA under the tensile mode is plotted and shown in Figure 8d. The stress−strain curve starts departing from linearity at an earlier stage and shows different slopes depicting the accurate elastic modulus of the developed composites.…”