Needle-punching is used as an alternative to expensive and sophisticated three-dimensional (3D) weaving processes to prepare a 3D composite. In this study, a 3D needled carbon–carbon (C/C) composite structure was examined using X-ray tomography and scanning electron microscopy (SEM). The effects of manufacturing porosities, needling diameter and needling density on the thermal conductivity of the composite were determined through multiscale finite-element modelling. The degradation of thermal conductivity caused by the manufacturing porosity was higher in the longitudinal direction than in the through-thickness direction. Moreover, it was found that the through-thickness thermal conductivity of the composites increased with increasing needling diameter and density.

Recrystallization of phosphorous deoxidised copper used for strength critical applications at elevated temperatures was investigated by means of in situ heated stage EBSD analysis using a Gatan Murano heated stage mounted within a Carl Zeiss Sigma FEGSEM electron microscope. The influence of applied strain as the result of deformation within a Nakajima test as an analogue for industrial forming on the recrystallization temperature was investigated, the impact of increased heating rates on microstructural evolution was also investigated. Inverse pole figure plots combined with regions of reduction in local misorientations and variations in geometrically necessary dislocations were used to establish the point of recrystallization and the recrystallized fraction of the material. Recrystallization was observed to occur at temperatures as low as 130 °C in highly strained samples compared to around 300 °C within the annealed samples dependent upon heating rate. Increased heating rates were observed to produce a finer final grain structure but had little effect on presence of 60° grain twins, which was influenced more by initial material condition. Graphic

This study set out to look at the influence of nickel additions on a commercially available AA7020 to understand the impact of the resultant intermetallics on recrystallization, formability and material strength. Elevated temperature tensile testing across a range of strain rates (5 × 10⁻⁴ s⁻¹ × 10⁻¹ s⁻¹) and three temperatures (450− 500 °C) to compare material ductility followed by gas bulge testing at 475 °C and two gas pressures to investigate formability in a test closer to industrial forming conditions. Material strength was established using standard tensile testing, and EBSD used to understand the microstructural evolution of the materials. It was seen that the nickel additions increased ductility of the material across all test conditions, coupled with increasing the material strength. This was achieved due to the formation of nickel rich intermetallics which refine the microstructure during pre-heating through particle stimulated nucleation and subsequently improve strength through precipitation hardening in aging treatments. Graphic

This study presents two analogs of extant industrial thermomechanical cycles to look at the microstructural evolution of C106 phosphorous deoxidized copper throughout. Vickers hardness testing was employed to assess the influence on post-formed mechanical properties. In situ heated stage EBSD analyses using a Carl Zeiss Sigma FEGSEM and Gatan Murano heated stage were employed to establish the temperature region where recrystallization initiates to better understand results from bulk post facto EBSD analysis.