The Project aim. The goal of the present project is to develop the new "Hydride Cycle" (HC) technique for synthesis of aluminides of refractory metals. HC has been elaborated at the Laboratory of High-temperature Synthesis and Technology of Inorganic Compounds of the Institute of Chemical Physics of Armenian National Academy of Sciences (SHS-Laboratory). In the frame of the present Project we are planning to study aluminides formation in HC, synthesize a wide range of these intermetalides in SHS-Laboratory, and to investigate some their physical and chemical characteristics in the Georgian Technical University, Republic Center for Structure Researches (RCSR).
Current status. The real bases for implementation of the present Project are the fundamental developments on synthesis of hydrides in SHS mode for many years. During prior study of the SHS processes in Me-H systems, and elaboration of high productive methods for syntheses of hydrides of transition metals, in SHS-Laboratory an idea has arisen concerning usage of metal hydrides as source materials for synthesis of metal alloys. This idea resulted in creation of a highly effective, previously unknown high efficient HC method for producing refractory metal alloys. Using HC, in Ti-Zr, Ti-Hf, Zr-Hf, Ti-Zr-Hf, Ti-V, Ti-Nb, etc. systems the alloys have been synthesized, among them – the alloys with structure of a-, a-, a- and u-phases. More than 100 alloys of refractory metals were synthesized. The interaction of formed alloys with hydrogen in SHS resulted in formation of their hydrides with high hydrogen content (Н/Ме ? 2).
Current methods of producing binary and multicomponent alloys are based on technologies of fusion (induction, arc fusion or electron-beam), or powder metallurgy, mechanical chemistry and SHS. All these methods are technically difficult, high power-consuming, laborious, long-term and multi-stage. The elaboration of new more effective processes is an actual problem of modern Material Science.
HC has significant advantages over these methods: a) low operating temperatures (800-1100оС instead of 1800-2600оС); b) short duration of alloy formation (1.5-2 hours instead of tens of hours); c) it is a one-stage and wasteless process; d) the source metal hydrides can be synthesized in the high-performance, low-energy consuming SHS process. All these provide a cheap, high-productive, easy, resource-conserving character of HC.
The formation of a refractory alloy in HC proceeds in the solid phase mechanism, avoiding the melting. During heating of compacted mixture of source metal hydrides, the Ме-Н bonds break and the strong activation of metals takes place. In the environment of liberated hydrogen, the oxide film, coating the fine-dispersion particles is reduced. «Open bonds» and purified surfaces of powder particles promote sold phase diffusion of metals, forming alloy. In our previous works HC has been successfully used in creation of aluminides of IV-V group metals of designed composition, provided with special physical and chemical characteristics..
Expected Results and Their Application. The proposed Project concerns both the fundamental and the applied researches. It is expected, that the results obtained in its frame will serve as the basis for creation of a series of new, pollution-free, high-performance, low power-consuming, high-tech innovation technological processes for synthesis of binary and multi-component aluminides of transition metals and their hydrides. We are planning to synthesize in HC a wide range of aluminides. The synthesis of intermetallic compounds and their hydrides in Ti-Al, Ti-Nb-Al, Ti-Nb-V-Al and other systems represents a special interest. These alloys can provide serious competition to nickel based super-alloys. The developed technology will be a subject of some commercial offers. The synthesized aluminides of refractory metals and their hydrides have wide potential of application: in high-tech branches of atomic and hydrogen energy, aerospace, chemical industry, machine industry, electronics, medicine, etc. The technological processes, designed in the Laboratory conditions, can be demonstrated at the Institute of IChPh ANAS.
Scope of activities. In the frame of the Project we are planning to synthesize in HC a wide range of aluminides. Some of the physical and chemical characteristics of more industrially important synthesized aluminides will be studied in SHS-Laboratory and RCSR, using X-ray, SEM-EDX, DTA, chemical and metallographic analyses. The corrosion tests in gas environment at high temperature (500-1200oС) will be conducted, the corrosion kinetic curves will be obtained and high-temperature strength/heat resistance of synthesized aluminides will be determined. Using the methods of low-frequency spectrum in the range of 20-900°C, the internal friction and shear modulus will be determined, which will allow finding the activation energy, diffusion coefficients, relaxation times, the critical strain amplitudes and the beginning of microplastic deformations in the test materials. The areas of effective application of HC-synthesized aluminides of different compositions will be forecasted.
Role of Foreign Collaborators/Partners. According to planned activity in the frame of the present Project, the below-listed forms of co-operation with foreign collaborators are proposed: information interchange; discussion of results during realization of the Project; carrying out of joint work-seminars in Yerevan and Tbilisi; presentation to ISTC office of collaborators’ comments to technical reports (quarter, annual, total, etc.) on the implementation of the Project; joint research and complex testing (certification) of most interesting alloys and their hydrides synthesized during Project implementation.
Technical approach and methodology. Real bases for implementation of the present Project at the Laboratory of High-temperature Synthesis of IChPh of Armenian NAS are the fundamental developments on synthesis of hydrides by SHS method and the recently elaborated essentially new HC method of alloys synthesis. The results of these prior investigations have revealed the prospects for the further study of processes of formation of multicomponent alloys, aluminides and their hydrides. The obtained results created also the real bases for the obtaining of anticipating new, hydrogen-induced, structures. Research experience of Georgian Technical University, Republic Center for Structure Researches (RCSR) in the field of material science, will permit authentically characterization the properties of the synthesized aluminides of transition metals. In the Project it is proposed to solve the fundamental and applied problems.mmary of the project.
