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Temperature is known to affect deformation mechanisms in metallic alloys. As temperature decreases, the stacking-fault energy in many face-centered cubic (fcc) alloys decreases, resulting in a change of deformation mode from dislocation slip to deformation twinning. Such an impact of temperature can be more complex in compositionally heterogeneous microstructures that exhibit, for example, local concentration fluctuation such as that in multi-principal element alloys. In this work, we compare the dislocation behavior and mechanical properties of a fcc Cr20Mn10Fe30Co30Ni10 high-entropy alloy at ambient and liquid-nitrogen temperatures. We find that a network of stacking faults is formed by uniformly extended dislocations at ambient temperatures with low stacking-fault energy, whereas at lower temperatures, uneven dissociation of dislocations becomes significant, which results in severe dislocation pile-ups together with their pronounced entanglement. Our findings indicate that as the stacking-fault energy decreases with decreasing temperature, the heterogeneity of the distribution of elements becomes more dominant in tuning the local variation of lattice resistance. As a result, the change in dislocation behavior at low temperatures strongly affects microstructural evolution and consequently leads to significantly more pronounced work hardening.

In this study, BNBT-KNN-xTa2O5 was designed and synthesized, successfully achieving a reduction in the relaxor-ferroelectric phase transition temperature. Synergy between temperature-dependent ferroelectric testing and dielectric spectroscopy confirmed that the depoling temperature gradually decreased with increasing doping concentration. Fitting of the relaxation parameter and freezing temperature substantiated that the incorporation of Ta2O5 increased the degree of relaxation in BNBT-KNN-xTa2O5, thereby effectively lowering the relaxor-ferroelectric phase transition temperature. [ABSTRACT FROM AUTHOR]

Developing environmental-friendly materials with high-density energy storage is of paramount importance to meet the burgeoning demands for energy storage. In this study, we harness the modulation of a multicomponent solid solution by introducing KNN as a third element into the BNT–BST system, thereby achieving a marked enhancement in both energy storage performance and the temperature stability of the dielectric constant. BNBST–4KNN stands out for its exceptional dielectric stability, with a dielectric constant variation rate within 10% across a broad temperature range of 4 0 ∘ C to 4 0 0 ∘ C, a feat attributed to the flattening and broadening of the T m peak. BNBT–2KNN exhibits superior energy storage capabilities, with an energy storage density of 1.324 J/cm3 and an energy storage efficiency of 72.3%, a result of the P–E loop becoming more slender. These advancements are pivotal for the sustainable progression of energy storage technologies. [ABSTRACT FROM AUTHOR]

Flexoelectricity in twinned ferroelastic thin films generates polarity inside twin walls. The electrical dipoles are typically aligned parallel to twin walls while out-of-plane dipoles are induced elastically by an atomic force microscopy (AFM) tip or by atomic steps in the substrate. Molecular dynamics modeling shows that the out-of-plane dipoles form polar vortex structures next to the domain walls. Flexoelectricity, e.g., by moving AFM tips, produces displacement currents inside these vortices. We estimate that these displacement currents generate magnetic fields with moments in the order of 10−9 μB per atomic layer. [ABSTRACT FROM AUTHOR]

Author(s): Suzhi Li [1, 2, 3]; Qunyang Li (corresponding author) [4, 5]; Robert W. Carpick (corresponding author) [6]; Peter Gumbsch [7, 8]; Xin Z. Liu [6]; Xiangdong Ding [1]; Jun [...]