Showing papers in "Acta Materialia in 1997"

TL;DR: The elastic and tensile behavior of high-density, high-purity nanocrystalline Cu and Pd was determined in this paper, showing that porosity increases with decreasing porosity, and may be significantly affected by a few large processing flaws.

TL;DR: In this article, the development of an ultra-fine grain size during equal-channel angular (ECA) pressing of high purity aluminum with an initial grain size of ∼1.0 mm was investigated.

TL;DR: In this article, the formation of deformation induced high angle boundaries is suggested based on grain subdivision processes which can lead to formation of different texture components within an original grain, and the distribution of their misorientations is estimated based on these mechanisms.

TL;DR: In this article, the deformation history of NiTi was established by photographically recording surface changes of a brittle coating as austenite-martensite phase transition fronts traverse the specimen.

TL;DR: In this paper, an analysis of the growth and stability of cellular microstructures, which takes account of the orientation dependence of boundary energies and mobilities, is presented and used to develop a simple unified theory of continuous and discontinuous recovery, recrystallization and grain growth.

TL;DR: A microscopic model for the formation of annealing twins in f.c. crystals is proposed in this article, where it is argued that Shockley partial loops nucleate on consecutive planes by growth accidents occurring on migrating {111} steps associated with a moving grain boundary.

TL;DR: In this paper, the authors assess the roles of cell morphology and of imperfections in governing the basic properties: stiffness, yield strength, and fracture resistance of three different commercially available closed cell Al alloys all made by foam casting.

TL;DR: In this article, the grain growth in nanocrystalline Fe produced by high energy ball milling is analyzed using two different models of grain growth, one of which takes pinning forces on the grain boundaries into account.

TL;DR: In this article, the authors investigated the kinetics of grain growth in two-dimensions (2-D) by computer simulations based on a continuum diffuse-interface field model and found that the time dependence of average grain radius follows the kinetic law: R¯mt −R¯m0 = kt with m = 2.

TL;DR: In this paper, a 3D continuum stochastic field kinetic model of martensitic transformations is developed, which explicitly takes into account the transformation-induced elastic strain, and the model is able to predict the major structural characteristics of Martensite during the entire transformation including nucleation, growth and eventually formation of internally twinned plates which are in thermo-elastic equilibrium with the parent phase.

TL;DR: In this article, the authors studied mild and severe wear behaviors of a wrought aluminium alloy (6061 Al) as a function of applied load and sliding velocity, and constructed an empirical wear transition map to delineate the conditions under which severe wear initiated.

TL;DR: In this paper, Japanese 9% Cr steel containing 0.5% Mo and 1.8% W (P92) has been investigated using TEM of thin foils and extraction double replicas.

TL;DR: In this paper, the influence of cold wire drawing on the structure of a pearlitic steel containing 0.7 wt% of carbon and subjected to a strain of approximately 3.5 has been studied.

TL;DR: In this paper, two-and three-dimensional (3D) cellular automata (CA) algorithms are proposed for modeling the growth of dendritic grains from the liquid phase.

TL;DR: In this paper, the origins of hardening in the artificially aged alloys Al1.1Cu 1.7Mg(0.1Ag) are presented.

TL;DR: In this paper, a scaling hypothesis was developed and applied to parameters describing the evolving deformation microstructure based on a physics analogy with nucleation and aggregation during thin film growth.

TL;DR: In this article, a simple theory which analyses discontinuous and continuous recovery, recrystallization and grain growth, and which enables the relationships between the various annealing phenomena to be explored, was extended to include the effects of a dispersion of second-phase particles.

TL;DR: In this paper, the nanoindentation fracture of amorphous carbon films on silicon substrate was studied and the fracture process was found to progress in three stages: (1) first ring-like through-thickness cracks form around the indenter by high stresses in the contact area; (2) delamination and buckling occur around the contact areas at the film/substrate interface by high lateral pressure; and (3) second ring-wise through-thinness cracks and spalling are generated by high bending stresses at the edges of the buck led film.

TL;DR: In this article, a new scheme to predict the intermetallic compound which forms first at the substrate/solder interface during the soldering process has been suggested, by calculating metastable equilibria between the substrate and the liquid solder phases and by comparing the calculated driving forces of formation for individual phases.

TL;DR: In this article, a technique is developed for measuring the flow stress of metals over a broad range of strains, strain rates, and temperatures, in uniaxial compression, in which a sample is subjected to a single stress pulse of a predefined profile, and then recovered without being subjected to any other additional loading.

TL;DR: In this paper, a two-dimensional model composite with elastic reinforcements in a crystalline matrix subject to macroscopic shear is analyzed using both discrete dislocation plasticity and conventional continuum slip crystal plasticity.

TL;DR: In this article, the intermetallic compound Mg2Ni was mechanically ground under a hydrogen atmosphere to synthesize a nanostructured composite material that is composed of nanocrystalline intra-grain and disordered inter-grain regions.

TL;DR: In this article, the temperature dependence of grain boundary (GB) self-diffusion in Cu polycrystals was systematically investigated using the 64Cu radiotracer and the serial sectioning technique.

TL;DR: In this paper, the peak hardness of alloy powders is associated with the concentration of the alloying element initially in solid solution in the powders and the strengthening observed is interpreted in terms of theories of precipitation and dispersion strengthening.

TL;DR: In this paper, the authors derived a general expression for the mean stress in a solid induced by the stresses of areal and linear defects such as grain boundaries and triple junction lines.

TL;DR: In this paper, a new wire-conductor fabrication method was developed for Cu Ag alloys containing 6-24 wt% Ag in which ultra-high strength and high conductivity were obtained by cold drawing combined with intermediate heat treatments.

TL;DR: In this article, a dynamic recrystallization model is proposed in which mechanically-driven subgrain rotations assist the mechanism for recrasing. But the model is not suitable for high strain, high-strain-rate conditions within shear bands.

TL;DR: In this paper, the microstructural change of supersaturated austenitic Fe 30.0wt%Mn 7.8wt%Al 1.3wt%C alloy on ageing at 823 K has been investigated by transmission electron microscopy (TEM) and X-ray diffraction.

TL;DR: A technique has been developed for making samples of steel with controlled additions of powdered mineral phases as discussed by the authors, which has been studied from the point of view of the acicular ferrite microstructure, which forms when ferrite plates nucleate heterogeneously on nonmetallic inclusions.

TL;DR: In this article, Voronoi cells resulting from Dirichlet tessellation of a planar heterogeneous microstructure are introduced as a unified tool in characterization and response modeling of multiphase materials.