From micro- to nano-scale molding of metals: Size effect during molding of single crystal Al with rectangular strip punches

Axisymmetric reverse extrusion experiments were conducted on annealed Cu rod specimens to form cup-shaped structures with sidewall thicknesses ranging from ∼400 µm down to ∼25 µm. Changes in Cu grain morphology, size, and texture were examined through scanning electron microscopy and electron backscatter diffraction (EBSD). Pole figure and orientation distribution function analysis of EBSD data showed the same texture components in the present small-scale metal forming experiments as those observed in macroscale sheet metal rolling. The plastic deformation became inhomogeneous as the characteristic dimension for extrusion decreased to ∼25 µm, such that the deformation process involved a small number of Cu grains. Extrusion force–punch displacement curves were measured as a function of extruded cup sidewall thickness and compared to outputs of a continuum plasticity finite element analysis in corresponding geometries. The present work illustrates materials characteristics in small-scale metal forming and suggests directions of future work for bringing improved correspondence between experimentation and modeling.

Assessing texture development and mechanical response in microscale reverse extrusion of copper

Nonlinear analysis of compact and thin-walled metallic structures including localized plasticity under contact conditions

Microchannel heat exchangers (MHEs) have become a leading candidate for applications demanding removal of highly concentrated heat, including cooling of future generation high-performance microelectronic and power-electronic modules. Metal-based MHEs offer potential advantages over silicon-based counterparts in terms of overall heat transfer performance and mechanical robustness. Low-cost fabrication of metal-based MHEs and quantitative evaluation of their liquid flow and heat transfer characteristics are essential for establishing the technical feasibility and economic viability of such devices. Adoption of metal-based MHEs in many applications demands quantification of liquid flow and heat transfer performance with application-relevant coolants, for example, ethylene glycol (EG)/water mixtures rather than pure water. As a first step in this direction, we report here fabrication and assembly of all-Cu MHE prototypes, as well as results of flow and heat transfer testing using pure water and pure EG as the...

J. Jiang

Papers

Quasi-static normal indentation of an elasto-plastic substrate by a periodic array of elastic strip punches