Analytic Binary Alloy Volume–Concentration Relations and the Deviation from Zen’s Law

Alloys expand or contract as concentrations change, and the resulting relationship between atomic volume and alloy content is an important property of the solid. While a well-known approximation posits that the atomic volume varies linearly with concentration (Zen’s law), the actual variation is more complicated. Here we use the apparent size of the solute (solvent) atom and the elasticity to derive explicit analytical expressions for the atomic volume of binary solid alloys. Two approximations, continuum and terminal, are proposed. Deviations from Zen’s law are studied for 22 binary alloy systems.

Powder Composition Structurization of the Ti-25Al-25Nb (at.%) System upon Mechanical Activation and Subsequent Spark Plasma Sintering

The results of a study of the microstructure evolution of pre-mechanically activated elementary powders based on the Ti-25Al-25Nb (at.%) compositions differing in the particle size of the aluminum (Al) component are presented. It was found that during the mechanical activation, most of the Al was dissolved in the Ti and Nb lattices by interpenetration with the formation of solid solutions (Ti, Al) and (Nb, Al). It has been established that an increase in temperature to 1400 °C, when sintering powder materials based on the Ti-Al-Nb system, leads to a sharp increase in the temperature of Al particles, as a result of the melting of which it is impossible to control the phase formation, which ultimately leads to the difficulty of obtaining the required product. It was determined that in the process of spark-plasma sintering of mechanically activated compositions, intermetallic compounds are formed based on phases ‒ α2, B2 and O, and with an increase in the sintering temperature, their morphology and distribution in the alloy volume change.

Creation of Submicroporous and Nanoporous Structures in Metallic Materials by Laser Thermocycling as Eutectic Is Reached

The possibilities of forming submicroporous and nanoporous structures in metallic materials by laser thermocycling as eutecticis reached were determined. With the implementation of the selected modes of laser treatment on L62 brass samples with a thickness of 50 µm leads to the formation of wrinkled relief, which indicates an increment of alloy volume in this area, that is, a porosity increment in the metallic material. Submicroporous and nanoporous structures are formed in the copper-zinc L62 alloy sample, which appear on the surface of the sample. Nanopores have a shape similar to equiaxial. Submicropores are formed as a result of nanopores merger. A relief is formed on the surface consisting of depressions having a shape similar to that of a hemisphere and a linear structure, oriented along the direction of rolling process.

Theoretical and Practical Aspects of Pneumatic Powder Injection into Liquid Alloys with a Non-Submerged Lance

The method of powder injection into molten metal has been widely known since tens of years and successfully utilized in various metallurgical processes. The most common is a solution with injection lance submerged under the liquid alloy surface, because it is easier apart from some of disadvantages of this approach. In this paper the authors’ complex experiments on the pneumatic injection process with non-submerged lance have been presented. The new approach on jet cone angle importance and its influence on the efficiency of the injection process has been shown. The issue of the effective jet radius that was proposed by former scientists as well as computer modelling and injection experiments recorded with high speed camera have been presented. The final comparison of the typical injection lance and developed by authors new lance with flange was presented, too. The benefits of use of a new one for the treatment of small liquid alloy volume (e.g. inoculation or alloys addition introduction) have been pointed.

Model Experiments with New Lance for Pneumatic Powder Injection

The paper presents the results of model experiments with new lance design. The lance was invented in Silesian University of Technology, Department of Foundry. It is dedicated for the pneumatic powder injection into liquid metal bath without lance submersion. The situation like that is common for small molten alloy volume when the problem of temperature decrease is significant. In such case the carrier gas introduction into metal as well as cooling with gas blowing onto metal bath surface should be avoided. The new lance was equipped with four parallel slots made on its outlet and a flange. This design causes the carrier gas evacuation before it reaches the molten metal surface. The article presents the model experiments made with use of the device for the diphase gas-powder jet forces recording. The comparison of two lances: normal steel pipe and this of new design was presented in the article, too.