New possibilities of recently constructed high-temperature solution calorimeter

Abstract

The calorimeter presented in this paper is constructed under supervision of authors. The most substantial innovation of construction of the device was introduction of intermediate container with ten sockets. As a result the calorimeter is used for determination of enthalpy of formation for alloys in a wide range of temperature (up to 1,400 K). As an example results from alloys from the Ni-Al-Cr system are presented, they are aimed to determine directly c 0 / c 0 ? c / c phase boundaries with use of this ''in situ'' calorimetric method. Precise indication of phase boundaries is crucial for determination of phase diagrams.

Direct Determination Of γ′ / γ′+γ / γ Phase Boundaries In Ni-Al-Cr System Based On Enthalpy Of Formation Results Obtained By Calorimetric Solution Method

“…As with the previously analyzed by the authors Ni 75 Al 25 ÷Ni 75 Cr 25 section [16], location of phase boundaries The work is a continuation of the research carried out on a high-temperature calorimeter solution type on alloys from Ni-Al-Cr system. Thanks to the construction innovation introduced by authors the device allows the determination of the formation enthalpy of alloys at ambient and elevated temperatures.…”

“…A consequence is, that lower input of energy is necessary for breaking the bonding between of atoms during solution in the case of disordered g phase and this fact is reflected on the higher formation enthalpy value of g phase. Just as was the case in studies of alloys of the Ni 75 Al 25 ÷Ni 75 Cr 25 section [16], formation enthalpy changes take place in stages. It allows dividing tested range into sections corresponding to the ranges of occurrence of the phases and gives the possibility to directly determine phase boundaries γ ′/ γ′+γ / γ.…”

“…Construction of this device as well as operating principle were described in previous works of the authors [16,17].…”

“…Enthalpy of formation is determined for temperature, from which sample is dropped into the bath. [16] and for temperatures 873K and 1150K from work of one of the author (K.R.) [22].…”

“…For this purpose, specially designed high temperature solution type calorimeter was used [16,17]. Thanks to the construction innovation in the form of intermediate container, allowing for long-term annealing of samples before dropping them into the bath, the device allows the direct determination of the formation enthalpy of alloys at temperatures up to 1400K.…”