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Abstract: Effect of solute atom on dislocation nucleation and subsequent elasto-plastic deformation observed in nanoindentation tests was investigated using Si-alloyed interstitial-free steel (IF). The onset shear stresses for plastic deformation τpat the first pop-in where the dislocation nucleation occur were greatly affected by the presence of solute Si irrespective of the Si content tested. The analysis of the cumulative probability of τpindicate that the dislocation nucleation occurred through heterogeneous nucleation where the nucleation sites are solute Si atoms. It has suggested that Si has ability to increase the activation energy for dislocation nucleation. The variation in the magnitude of displacement burst at the first pop-in showed that more kinetic energy of moving dislocations is dissipated by the presence of solute Si resulting in decrease of travel distance of dislocations. This trend can be explained by classical solid solution theory. The staircase yielding observed only in Si-alloyed sample indicate that the re-activation of dislocations formed at the pop-in became difficult by the solute Si. Graphic Abstract:

Abstract: By employing mechanical rejuvenation, we demonstrated that the viscoelastic deformation become visible in macroscopic tensile test. The clear tensile strain rate dependence of yield stress was observed only in the rejuvenated sample, showing that the macroscopic elongation is governed by the thermally activated process. Activation volumes estimated from the mechanical responses during the macroscopic tensile test and microscopic nanoindentation test showed consistent values. The rejuvenated sample having tensile ductility showed larger STZ volume comparing with the relaxed samples. These results indicate that the fraction and connectivity of liquid-like regions in BMG can be controlled by appropriate use of mechanical rejuvenation. Graphical abstract:

The nanostructure of oleyl acid phosphate (OLAP) in lubricant, which is an essential factor for understanding lubrication properties, was investigated using small-angle X-ray scattering (SAXS). SAXS profiles were observed for OLAP with concentrations of 1, 3, 5, and 10 mass % in poly-a-olefin (PAO). The SAXS results demonstrated that OLAP forms reverse-micellar-like aggregates in PAO. This nanostructural information from SAXS will drive further development of advanced lubricants.Small-angle X-ray scattering (SAXS) was used to measure the nanostructure of oleyl acid phosphate (OLAP) in lubricant, which is essential for understanding lubrication properties. The SAXS results show that OLAP forms reverse-micellar-like aggregates in poly-a-olefin. This nanostructural information from SAXS will drive further development of advanced lubricants.