It is well-known that cell morphology plays a vital role in the mechanical properties of the closed-cell aluminum foam. In this work, a three-dimensional (3D) realistic structure was obtained by using the synchrotron X-ray micro-tomography technique and then translated into a numerical model for a further finite-element simulation. In order to investigate the early compressive deformation in the closed-cell aluminum foam, we chose three different strain levels, namely, 0.2% (initiation of plastic strain), 2.8% (propagation of plastic strain band), and 6% (formation of collapse band) to discuss the evolution forms of plastic strain concentration by simulation. We found that the curvature, anisotropy, and distribution of cell volume of adjacent cells played a vital role in the initiation of plastic strain. Furthermore, the phenomenon that plastic strain band propagated along the direction aligned 45° with respect to the orientation of the compression was also investigated in the propagation of the plastic strain band and formation of the collapse band. Finally, the comparison between experimental results and simulation results was performed to illustrate the early location of these three different levels in the whole compressive deformation.

The fabrication of Ti-aluminide multi-layered composites have attracted great attention for their excellent mechanical properties, such as high specific strength, high specific stiffness, tolerable toughness, and low density. The preparation of the composite produced by a hybrid procedure composed of Vacuum Hot Pressing (VHP) and Hot Isostatic Pressing (HIP) using Ti foils and Al foils has been performed. Further, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray Spectrometry (EDXS) were carried out to identify the microstructure and phase formation of the composite. In addition, an in-situ three-point bending test was conducted on the notched specimen to observe the crack propagation behavior carefully. The results indicate that the densified composite was obtained without any apparent voids and pores which could undesirably develop into the source of cracks. Furthermore, all the pure Al foils were totally consumed to form a series of the Ti-Al compounds through the diffusive reaction between the adjacent Ti and Al foils. Moreover, the in-situ observation demonstrates the initiation and propagation of cracks in the intermetallic layers and the role of residual Ti layers to blunt and bridge the cracks by their plastic deformation. This study provides a new strategy for fabricating the Ti-aluminide multi-layered composites.

Finite element analysis was conducted on a thermally-aged cast duplex stainless steel based on the true three-dimensional (3D) microstructure obtained from X-ray microtomography experiments and using the constitutive behavior of each individual phase extracted from nanoindentation on single-crystal and bicrystal micropillar compression tests. The evolution of the phase morphology, the mechanical properties and the boundary deformation behavior during the aging process are highlighted. Quantitative analysis in terms of the distribution and evolution of the stress and strain in both the as received and aged conditions was performed. The experimental results show that aging at an intermediate temperature has a negligible influence on the morphology of the two phases in cast duplex stainless steel (CDSS). Results from simulations reveal that the mechanical behavior of this material were seriously affected by the microstructure and the mechanical properties of the individual phase and the necking deformation tend to form in the area with less large ferrite grains after aging. In addition, stress localization tends to form at the austenite/ferrite interface, in the narrow region of ferrite grains and in the small ferrite grains.