Structure and properties of Ta-Zr alloy obtained by high-speed melt quenching from liquid state

Abstract

The paper considers the effect of Ta-Zr binary system splat quenching implemented by the method of pendant drop melt extraction. The study was conducted using two mixtures of tantalum and zirconium elementary powders with a content of 60 and 6 % of tantalum respectively. After mixing, the compositions were pressed at 250 MPa in a steel mold on a hydraulic press. Sintering was carried out in a vacuum furnace at 1350 °C and a pressure of 10-3 Pa. Splat quenching was carried out in a vacuum at 2•10-2 Pa using electron-beam heating and a spinning disk absorber. Resulting fiber thickness was 15 to 80 gm. The results of testing splat-quenched Ta—Zr alloy discrete fibers and samples formed as a result of rod stock melting by electron-beam heating (as-cast) were studied and compared. It was found that the structure of splat-quenched fibers of the alloy with a Ta content of 6 wt.% consists of 5—10 gm needle-shaped grains, and the alloy with a Ta content of 60 wt.% has a columnar dendritic structure. A study of tantalum and zirconium distribution across the fiber cross-section showed that cooling rate reduction to less than 105 K/s leads to monotectoid transformation in the alloy with a tantalum content of 60 wt.%. It was found that for an alloy with 6 wt.% Ta the fiber microhardness value is 1.5 times higher in comparison with the same alloy without quenching, and for an alloy with Ta 60 wt.% it is higher by a factor of two.