Early Stages of Nanostructuring of a Pearlitic Steel by High Pressure Torsion Deformation

High-pressure torsion of a pearlitic steel under a pressure of 7 GPa and for 1 rotation produces a highly deformed pearlitic structure. Some regions are less deformed with straight lamellae and resolvable dislocations, whereas other have more buckled lamellae and the ferrite appears to have a nanoscale cell structure with each cell slightly misoriented from its neighbours. In all cases, the cementite lamellae still contain most of the carbon but are broken into a nanocrystalline structure. 3D atom probe analyses show that the cementite is losing carbon, and that some of this appears to be transported along dislocations into cell wall structures. The deformation mechanisms and the early stages of the destruction and dissolution of the cementite are discussed

Surface tension and viscosity of liquid Pd43Cu27Ni10P20 measured in a levitation device under microgravity

Here we present measurements of surface tension and viscosity of the bulk glass-forming alloy Pd43Cu27Ni10P20 performed during containerless processing under reduced gravity. We applied the oscillating drop method in an electromagnetic levitation facility on board of parabolic flights. The measured viscosity exhibits a pronounced temperature dependence following an Arrhenius law over a temperature range from 1100 K to 1450 K. Together with literature values of viscosity at lower temperatures, the viscosity of Pd43Cu27Ni10P20 can be well described by a free volume model. X-ray diffraction analysis on the material retrieved after the parabolic flights confirm the glassy nature after vitrification of the bulk samples and thus the absence of crystallization during processing over a wide temperature range