Liquid metal

About: Liquid metal is a research topic. Over the lifetime, 6947 publications have been published within this topic receiving 77785 citations. The topic is also known as: liquid alloy & liquid metal alloy.

A method to study the history of a double oxide film defect in liquid aluminum alloys

Abstract: Entrained double oxide films have been held responsible for reductions in mechanical properties in aluminum casting alloys. However, their behavior in the liquid metal, once formed, has not been studied directly. It has been proposed that the atmosphere entrapped in the double oxide film defect will continue to react with the liquid metal surrounding it, perhaps leading to its elimination as a significant defect. A silicon-nitride rod with a hole in one end was plunged into liquid aluminum to hold a known volume of air in contact with the liquid metal at a constant temperature. The change in the air volume with time was recorded by real-time X-ray radiography to determine the reaction rates of the trapped atmosphere with the liquid aluminum, creating a model for the behavior of an entrained double oxide film defect. The results from this experiment showed that first oxygen, and then nitrogen, was consumed by the aluminum alloy, to form aluminum oxide and aluminum nitride, respectively. The effect of adding different elements to the liquid aluminum and the effect of different hydrogen contents were also studied.

Electrohydrodynamic spraying to produce ultrafine particles

Abstract: Amorphous or microcrystalline alloy powder is prepared by the rapid quenching of ultrafine metallic spheroids generated from the molten metal state. The molten metal droplets are formed when an intense electric field (10 5 V/cm) is applied to the surface of liquid metal held in a suitable container. The interactions between the intense electric field and liquid surface tension disrupts the metal surface, resulting in a beam of positively charged droplets. The liquid metal spheres generated by this electrohydrodynamic process are subsequently cooled by radiative heat transfer. Rapid cooling of the droplets may be accomplished by heat transfer to a low pressure gas by free molecular heat conductivity. Quenching rates exceeding 10 6 °K./sec are possible using this technique. Thin film coatings are prepared by electrohydrodynamically spraying a beam of charged droplets against a target (substrate). The target can be electrically controlled to effect the charged particles impact. The materials to be sprayed electrodynamically can be varied in both throughput and species such that a target can have multimaterial layers being deposited coincidentally or sequentially. The ultra small droplet size will enhance the physical properties by reducing skin stresses and enhance the optical properties by reducing the growth of crystallites in the film. Precise layers can be deposited from extremely thin films to thick filters for optical characteristics into the infrared. All materials that can be molten and contained can be electrohydrodynamically sprayed and controlled for depositions upon a substrate material.

Thermal conductivities of molten metals: Part 1 Pure metals

Abstract: Thermal conductivity data for molten metals, published since the review of Touloukian et al. in 1970, are collated and evaluated. Where possible recommended values are given. Where availability of data permits, the Wiedemann-Franz-Lorenz equation relating electrical and thermal conductivities has been assessed. It has been found to be valid for most pure metals at their melting point.

Pressure infiltration casting of metal matrix composites

Abstract: Pressure infiltration casting ∗ is a unique form of liquid infiltration which utilizes pressurized inert gas to force liquid metal into a preform of reinforcement material. The methods and equipment used for pressure infiltration casting allow for inexpensive development of composite materials, prototypes, and net-shape component production. Pressure infiltration casting's use of an enclosed die chamber with controlled pressurization makes it possible to cast in low strength molds with high infiltration pressures. The development of a number of solidification systems has enabled parts to be infiltrated and directionally solidified, producing high quality composites. The basic principles behind pressure infiltration casting and its history will be discussed in this paper. Results of research in different methods for casting composites will also be presented. These methods include: 1. (1) top fill casting-liquid metal is forced downward by a pressurized gas into a preform; 2. (2) bottom fill casting-liquid metal is forced up a fill tube into a preform by pressurized gas acting on the surface of a melt; 3. (3) top pour casting-a method developed for infiltration of high temperature alloys where the reinforcement and melt must be prevented from reacting. The methods and apparatus illustrated include sample components with aluminum and copper matrices, their microstructures, and tolerancing for net shape component production.