LAUSR

Abstract The use of Ni-Al alloys proves to be highly relevant in advanced radiant burner production. The aim of this study is an in-situ fabrication of maсro-porous B2-L12 Ni-Al alloys by self-propagating high-temperature synthesis for a specified burner configuration. It has been revealed that the use of small amounts of special additives dramatically affects the synthesis of coarse-porous alloys. High-speed imaging and high-speed spectral pyrometry have demonstrated that a combustion wave consists of a set of short-lived superadiabatic drops of a melt, the temperature of which exceeds the liquidus temperature for a short time. In the formation of melt drops, up to 107 nickel and aluminum particles are involved. This makes it possible to synthesize porous alloys with Ni-Al elements of up to several millimeters in diameter, using Ni and Al powders with the size of fewer than 10 μm. The porosity structure of such alloys has been characterized in the paper. It has also been demonstrated that the structure can be controlled by changing initial synthesis conditions such as reaction mixture composition, an additive type and its amount, mixture relative density, and a preheating value. In addition, the article describes the conditions that allow obtaining alloys with Ni-Al elements in the range of 500–2500 μm in size. As for the phase composition of synthesized alloys, it has been examined by X-ray diffraction. Besides B2-L12 phases, the alloys may contain some martensite L10, which disappears if the alloys are annealed for an hour at a temperature of 1100 °C. To evaluate mechanical properties of the synthesized and annealed alloys, a compression test has been applied. The impact of the alloys phase composition on possible operation modes of Ni-Al radiant burners has been discussed in the work.