High-pressure phases in the Al86Ni6Gd4Tb2Er2 alloy

Abstract

The combination of various extreme influences (ultrahigh pressures, torsion under pressure and equal channel angular pressing, ultralow and ultrahigh temperatures, strong electric and magnetic fields, ultrafast cooling from the melt) allows us to significantly expand the region of metastable states and to obtain materials with different structural hierarchy: amorphous, quasi-and nanocrystalline. The key extreme parameter in the work is high pressure. High pressure phases are thermodynamically stable at high pressures. The methods of X-ray diffraction analysis and electron microscopy were used to study the structure, elemental, and phase composition of the hypereutectic Al 86 Ni 6 Gd 4 Tb 2 Er 2 (hereinafter, at.%) alloy during solidification of the melt at a rate of 1000 deg / s under ultrahigh pressure of 3 and 7 GPa. Samples for research were obtained in a high-pressure chamber of the toroid type. The alloy was heated and melted by passing alternating current through the sample. The structure of all the obtained samples is homogeneous, dense, without shrinkage shells. Solidification of the melt under pressure of 3 and 7 GPa leads to a change in the phase composition of the alloy, the alloy remains hypereutectic. At a pressure of 7 GPa, metastable crystalline phases were obtained. The combination of high solidification rate and mechanical compaction made it possible to obtain alloys with a crushed structure and high density. The average microhardness of samples obtained under pressure is ~4 times higher than the microhardness of the initial sample due to solid-solution and dispersion hardening. Despite the fact that the alloy is glass-forming, amorphous phases were not detected under the selected solidification conditions.

Влияние высоких давлений на формирование новых соединений в сплаве Al-=SUB=-86-=/SUB=-Ni-=SUB=-2-=/SUB=-Со-=SUB=-6-=/SUB=-Gd-=SUB=-6-=/SUB=--=SUP=--=SUP=-*-=/SUP=--=/SUP=-

“…Слиток состава Al 86 Ni 2 Со 6 Gd 6 получали сплавлением металлов в корундовых тиглях в печи Таммана. Исход- [11][12][13]. Ясно, что для подробного изучения полученных новых фаз интересно провести дополнительные исследования.…”