Hardening of Additive Manufactured 316L Stainless Steel by Using Bimodal Powder Containing Nanoscale Fraction.

The particle size distribution significantly affects the material properties of the additively manufactured parts. In this work, the influence of bimodal powder containing nano- and micro-scale particles on microstructure and materials properties is studied. Moreover, to study the effect of the protective atmosphere, the test samples were additively manufactured from 316L stainless steel powder in argon and nitrogen.

The Effect of Pre-Annealing on the Evolution of the Microstructure and Mechanical Behavior of Aluminum Processed by a Novel SPD Method.

A novel continuous process of severe plastic deformation (SPD) named continuous close die forging (CCDF) is presented. The CCDF process combines all favorite advances of multidirectional forging and other SPD methods, and it can be easily scaled up for industrial use. Keeping constant both the cross section and the length of the sample, the new method promotes a refinement of the microstructure.

Microstructure changes in ultrafine-grained nickel processed by high pressure torsion under ultrasonic treatment.

Commercially pure nickel was processed by high pressure torsion (HPT) and subjected to ultrasonic treatment (UST) with different amplitudes of compression-tension stresses in the zone of stress antinode of a standing wave. It was found that microstructure parameters such as the dislocation density, low- and high-angle grain boundary fractions, microhardness, and the stored excess energy as well, non-monotonically depend on the ultrasound amplitude. A structure relaxation leading to a reduction of internal stresses and stored energy and increase of the fraction of high-angle boundaries was observed at some intermediate amplitudes of the oscillating stress.

First experimental observation of shear induced hcp to bcc transformation in pure Zr.

Shear stresses are shown to induce the alpha (hcp) to omega (simple hexagonal) plus beta (bcc) transformation in pure Zr at room temperature. The beta Zr thus fabricated is stable at 1 atm and room temperature. This phase has so far only been found to occur at high pressures (P>30 GPa) and/or at high temperatures (T>1135 K).

Cellular and molecular interactions between MC3T3-E1 pre-osteoblasts and nanostructured titanium produced by high-pressure torsion.

Ultra-fine surface features are commonly used to modulate cellular activity on a variety of materials. The continuing challenge for materials in contact with bone is the development of a material with both favorable surface and bulk properties to modulate not only the cell-substrate interactions, but also to ensure the long-term stability of the implant. In a combined approach involving material sciences and cell and molecular biology, the nature and mechanism of cell-substrate interaction, in particular, the molecular machinery controlling cell response to the surface of the nanostructured titanium based material produced by the high pressure torsion (HPT) process is assessed.