Prof. Svetlana G. Menshikova
Udmurt Federal Research Center, Russia
Title: Influence of extreme (thermobaric) impacts on the structure and properties of Al-TM-REM alloys during cooling of their melts
Abstract:
Progress in understanding the processes
of structure formation occurring in melts of the Al-TM-REM type (TM-transition
metal, REM-rare earth metal) in the field of eutectics, as well as in studying
the influence of extreme effects (high pressures, temperatures and cooling
rates) on their processes hardening has a high scientific significance and
relevance.
The main types of high pressure chambers
used in Russia and abroad are considered.
The structure and properties of
aluminum-based alloys of binary Al-TM systems, as well as binary and
multicomponent glass-forming Al-REM, Al-TM-REM alloys and high-entropy
AlNiCoFeCr alloys are studied during the rapid solidification of their
high-temperature melts in a toroid-type high-pressure chamber. The possibility
of forming а new phases in alloys is investigated. The temperature range is
from liquidus temperature to 2000 K. The pressure range is from atmospheric to 10
GPa. Scheme of the experiment: setting the pressure → pulsed heating → holding at the set pressure and
temperature →
rapid cooling without depressurizing to room
temperature →
reducing the high pressure to atmospheric. The cooling rate is 1000 deg/s.
At pressures above 7 GPa and temperatures
of the order of 1800 K, new metastable compounds are formed in the alloys, which
persist for a long time under normal conditions. Depending on the production
mode, the mechanisms of melt
solidification change, and abnormally
supersaturated solid solutions are formed in the alloys. The samples are
homogeneous, dense, no pores and shrinkage cavities were found. The structure
is finely dispersed with high mechanical properties. High pressure increases
the glass-forming ability of the alloys.
Keywords: Al-based alloys, High pressure,
Metastable phase, Thermobaric treatment, Microstructure
Biography: