Occurrence of the Portevin Le-Chatelier effect in open-cell microcellular Al-2 wt% Mg

Microcellular open-cell metal foams with pores of 75 or 400 pm in diameter and made of pure Al or Al-2 wt% Mg are tested in compression. The aluminum foam exhibits a typical smooth plastic flow and a positive strain rate sensitivity, whereas plastic instabilities and a negative strain rate sensitivity appear in the stress-strain curves of the Al-2 wt Mg foams, indicating the presence of the Portevin Le-Chatelier (PLC) effect. The effect is further confirmed by acoustic emission analysis.Taken together, the data indicate that the PLC effect is caused in this material by the sudden collective deformation of many struts across the material. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Acoustic Emission Study of the Deformation Behavior of Mg-Mn Alloys Containing Rare Earth Elements

Magnesium-manganese (Mg-Mn) based alloys with various chemical composition were processed by indirect extrusion at two different speeds. Alloying with Mn and rare earth elements has significant influence on the microstructure and on the texture of the alloys under investigation. This paper deals with the acoustic emission analysis of the deformation behavior of the extruded Mg-Mn alloys. The acoustic emission measurements were performed during the uniaxial tension and compression tests, and the obtained results are discussed with respect to the influence of rare-earth elements on the deformation behavior, particularly in terms of the activation of dislocation glide and twinning

Atmospheric plasma spraying of functionally graded steel/tungsten layers for the first wall of future fusion reactors

Functionally graded steel/tungsten layers may be used as interlayers in the first wall of future fusion reactors tobalance thermally-induced stress peaks in the steel‑tungsten joint. In this work, a modified water-stabilizedatmospheric plasma spraying set-up is used to deposit uniform and functionally graded steel/tungsten coatings atelevated substrate temperatures. Uniform coatings were used to characterise individual sublayers of gradedcoatings in detail. The thermal expansion, thermal conductivity, Young's modulus and yield strength of thelayers are promising for the application in steel‑tungsten joints and can be explained by microstructural observations.Only at a substrate preheating temperature of 900°C the formation of intermetallic precipitatesduring deposition was observed