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Colloidal nanocrystals that consist of an inorganic core and an organic ligand shell can be assembled into architected nanocomposites. A wide range of mechanical properties can be achieved by tuning structural parameters such as sample dimensions, ligand length, and nanocrystal packing density. This review article describes the fabrication, structural characterization and nanomechanical testing of...
As nickel sulfide deposits are exhausted, it becomes necessary to mine and process low-grade laterite ores to satisfy the need for nickel production. To achieve an efficient extraction of Ni, Fe and Co, additives such as chlorides, sulfur and sulfates, alkali oxides, fluorides, sodium carbonate and sodium hydroxide are introduced into the extraction process, and are applied in the reduction roasting-magnetic...
This study compares thermal aging effects in Inconel 690 (IN690) produced by forging and powder metallurgy with hot isostatic pressing (PM-HIP). Isothermal aging is carried out over 400–800°C for up to 1000 h and then metallography and nanoindentation are utilized to relate grain microstructure with hardness and yield strength. The PM-HIP IN690 maintains a constant grain size through all aging conditions,...
TiAl alloy powders were simply and economically prepared by reactive synthesizing of elemental powders in molten salt, and the synthesis process and powder characteristics were investigated . The results showed that the reaction in the molten salt was completed when the temperature was heated to 750°C. A higher content of salt resulted in a decreased particle size and the optimum content of salt for...
Copper/diamond composites have great potential to lead the next generation of advanced heat sink materials for use in high-power electronic devices and high-density integrated circuits because of their potential excellent properties of high thermal conductivity and close thermal expansion to the chip materials (e.g., Si, InP, GaAs). However, the poor wettability between copper and diamond presents...
In order to improve the stretch formability of magnesium alloy sheets, {10–12} tension twins were introduced by pre-compression along the rolling (RD) and transverse directions (TD) with 1.6%, 3.3%, and 5.4% strain levels. Subsequent annealing at 473 K was conducted for 6 h to preserve twinning lamellae. In order to avoid bending–buckling, a special fixture for thin sheet compression has been developed...
A three-dimensional discrete phase model–volume of fluid coupled model has been developed to study the argon/steel/slag/air multiphase flow and mixing phenomena in an industrial gas-stirred ladle taking the coalescence, expansion and breakup of the argon bubbles as well as the fluctuant slag layer into account. The simulated results of the flow rate and bubble size evolution of the water model, as...
The Center for Predictive Integrated Structural Materials Science (PRISMS Center) is creating a unique framework for accelerated predictive materials science and rapid insertion of the latest scientific knowledge into next-generation ICME tools. There are three key elements of this framework. The first is a suite of high-performance, open-source integrated multi-scale computational tools for predicting...
Single-pass compression experiments have been performed on 51CrV4 spring steel using a Gleeble 3800 thermomechanical simulator at temperatures in the range of 800–1000°C and strain rate of 0.01 s−1 or 0.1 s−1; the maximum deformation degree was 50%. By considering the inflection of the ln θ–ε curve and minimum value of the − ∂(ln θ)/∂ε–ε curve, the relationship between the critical strain (εc) of...
Natural fibers such as those from sugarcane bagasse may be obtained as industrial waste products. These fibers have recently been investigated as low-cost reinforcements in composites for engineering applications, some of which may require exposure to temperatures above ambient. In the present work, fibers extracted from sugarcane bagasse were used at up to 30 vol.% as reinforcement in polyester-matrix...
Acid leaching of spent molybdenum (Mo) catalyst followed by a simple pH-selective precipitation route for recovery of Co-Mo sulfide/oxide complexes in high yield has been investigated. The effect of leaching parameters such as temperature, pulp density, particle size, time, and acid concentration on the dissolution efficiency of aforesaid metal ion was studied, revealing that the Mo and Co dissolution...
A simple and effective method for the removal of impurities from large-sized particle metallurgical-grade silicon (MG-Si) powders based on Cu-catalyzed chemical leaching (CuCCL) has been proposed and discussed. The leaching behaviors of the main metallic impurities (Fe, Al, Ca, Ti, Ni, V and Cu) were investigated using various leaching approaches. The typical precipitates at Si grain boundaries before...
The effects of current density on the multiphase fluid flow and solidification in the electroslag remelting (ESR) system are numerically investigated using the 3D mathematical model. The results show that with the increase of current density, the remelting rate of the consumable electrode increases and the dropping behavior of the molten metal at the electrode tip changes from discontinuous droplets...
In a bottom-blown copper smelting furnace, the longitudinal wave formed on the bath surface plays an important role in slag tapping and settling of matte droplets entrapped in the slag layer. This study employs a laboratory-scale cold model of a bottom-blown copper smelting furnace to investigate the features of the longitudinal wave on the molten bath surface during smelting. Experimental variables,...
Victoria Miller and Sean Agnew are the JOM advisors for the Magnesium Committee of the TMS Light Metals Division, and guest editors for the topic Integrated Computational Materials Engineering of Magnesium.
The ability to manufacture at the point of need in austere environments is a very important concept for the military. Research at the US Army Research Laboratory (ARL) is showing that agile, expeditionary manufacturing could be accomplished through use of materials at or near to the location of operating bases. These materials could include not only organic and inorganic materials naturally occurring...
A transient 3D mathematical model was developed to simulate oxidation of lanthanum during the electroslag remelting process, by which the electromagnetic field, fluid flow, heat transfer, and mass transfer were fully coupled via user-defined function. The formation and motion of droplets in the slag disturbed the distribution of the electric current density as well as the distribution of Joule heat...
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