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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. [ABSTRACT FROM AUTHOR]

PbS quantum dots/multiwalled carbon nanotube (PbS/MWCNT) heterostructures were fabricated via a simple wet-chemical method. The structural and optical properties of as-prepared samples were characterized by transmission electron microscopy, x-ray diffraction, micro-Raman, and photoluminescence spectroscopies. It was found that the size, shape, and coverage density of the PbS quantum dots on the MWCNT can be controlled through varying synthesis conditions. Photoluminescence spectrum revealed that the emission of the PbS quantum dots was partially quenched when they were coupled to the MWCNT. This suggests that the photoinduced charge transfer may occur between the PbS and the MWCNT. [ABSTRACT FROM AUTHOR]