Cast Intermetallic Alloys and Composites Based on Them by Combined Centrifugal Casting—SHS Process
This work aims to establish a scientific and engineering background in the production of cast multicomponent alloys and metalmartix composite (MMCs) via Self-Propagating High Temperature Synthesis (SHS, combustion synthesis) which is a novel process technique regarding fast and low-cost production ability. We carried out the search for reactive systems and process parameters that would ensure preparation of cast multicomponent materials in a single process. The principles and methods of the SHS thermite-type reaction processes have been investigated under high-gravity values applying loads up to 1000 g with special centrifuge set-up. In this way we expected to improve the yield of target product, remove gaseous byproducts, diminish the grain size in the product, and make product composition more uniform. The obtained results can be expected to make a theoretical background for industrial-scale manufacturing of heat-resistant intermetallic alloys, master alloys, catalysts, MMCs etc.
Development of very high strength Mo2NiB2 complex boride base hard alloy
Abstract A previous investigation revealed that additions of Cr and V to the Mo2NiB2 complex boride base hard alloy changed the boride phase crystal structure from orthorhombic to tetragonal and resulted in a remarkable improvement of mechanical properties associated with microstructural refinement. Moreover, an addition of Mn turned out to be effective in further improvement of the mechanical properties in the V-containing alloy. In this investigation, Ni–5B–xMo–12.5V–2.5Mn (mass%) model alloys with four levels of Mo contents corresponding to Mo/B atomic ratio ranging from 1.0 to 1.3 were prepared to study the effect of the Mo/B atomic ratio on the mechanical properties and microstructure. The results indicated that transverses rupture strength (TRS) increased with increasing Mo/B atomic ratio and showed a maximum value of 3.2 GPa at Mo/B=1.2 and then decreased with increasing atomic ratio. Hardness increased linearly from 86.8 HRA to 90.8 HRA with increasing Mo/B atomic ratio.
Electroless deposition of iron-boron alloys
Iron-boron deposits on a copper substrate were obtained by electroless plating. The films were prepared on the substrate which was immersed in a bath containingferrous sulphate, sodium potassium tartrate, sodium hydroxide and potassium borohydride and contacted with an aluminium strip. The plating mechanism is a combination of galvanic and chemical deposition due to reduction of the Fe cation by BH 4 - accompanied by boron codeposition. The effects of the concentration of ligand and reducing agent, pH value and temperature on the deposition rate and boron content were studied