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.

Silver, silver alloys, and composites with silver matrix are used mainly as electric contacts, circuit-breakers, and slide bearings. Contacts working conditions require as high as possible thermal and electrical conductivity, wear resistance during electric arc work, low susceptibility to tacking, and chemical stability. Unreinforced silver alloys do not meet those expectations, hence increasing interest in metal matrix composites. Reinforcing with ceramic particles improves tribological wear resistance and minimizes formability of silver alloys. At the same time, introduction of ceramic particles decreases thermal and electrical conductivity. In this paper, manufacturing method of silver-based composites reinforced with particles Al2O3, SiC, and glassy carbon was described. Composites were subjected to differential thermal analysis. Furthermore, thermal diffusivity measurements using laser flash method, as well as measurements of linear thermal expansion coefficient using dilatometric method were performed in order to determine heat conductivity of the prepared composites.

The main thesis of the research was the problem concerning calibration of high-temperature solution calorimeter with aluminum. The important assumptions applied at calibration of a device with aluminum were verified. Enthalpy values determined during the experiment clearly suggest that the level of deformation and diameters of aluminum samples used for calibration are negligible. The assumption that the temperature of the samples at the moment they reach the bath level is very close to room temperature, is appropriate.Keywords: high-temperature solution calorimeter, calibration, aluminum, enthalpy W pracy badano problemy dotyczące istotnych zagadnień związanych z kalibracją wysokotemperaturowego kalorymetru typu rozpuszczania za pomocą aluminium. Sprawdzono założenia wprowadzane przy kalibracji przyrządu z wykorzystaniem tego metalu. Wyznaczone podczas eksperymentów wartości entalpii świadczą, że nie ma znaczenia stopień odkształcenia oraz średnica użytych do kalibracji próbek aluminiowych. W tym ostatnim przypadku potwierdza to słuszność istotnego założenia, że próbki w momencie osiągania poziomu kąpieli mają temperaturę bardzo zbliżoną do temperatury pokojowej.

DSC analySIS of orDer-DISorDer tranSItIon In ni3al baSeD alloyS from ni-al-Cr SyStemAnAlizA DSC przemiAn typu porząDek-nieporząDek w StopACh nA oSnowie ni3al z ukłADu ni-al-CrNi-Al-Cr system is significant for industrial alloys based on intermetallic phase Ni3Al, that crystallizes in crystal lattice L12. It is indicated as γ′, contrary to disordered phase γ which occurs with addition of chromium. DSC analysis was performed on alloys of chemical composition from Ni75Al25÷Ni75Cr25 range of Ni-rich part of Ni-Al-Cr system. In addition, few measurements were conducted using DTA method. Based on curves registered, it was possible to identify characteristic temperature during heating and cooling of the sample. It corresponds to existence of phase boundary γ′+γ / γ in examined alloys. Results of thermal analysis were compared with results obtained with other method performed by authors which is solution calorimetric method.Keywords: Ni-Al-Cr system, intermetallic phase Ni3Al , order-disorder, DSC analysisUkład Ni-Al-Cr jest ważnym układem dla przemysłowych stopów na osnowie fazy międzymetalicznej Ni3Al, która krystalizuje w uporządkowanej sieci L12. Oznacza się ją jako γ′ w odróżnieniu od fazy nieuporządkowanej γ, która pojawia się wraz z dodatkiem stopowym chromu. Wykonano serię stopów, których skład chemiczny leży na linii Ni75Al25÷Ni75Cr25 w bogatej w nikiel części układu Ni-Al-Cr i poddano je analizie DSC. Dodatkowo wykonano kilka pomiarów metodą DTA. Na podstawie zarejestrowanych krzywych udało się zidentyfikować charakterystyczne temperatury podczas nagrzewania i studzenia próbki. Odpowiadają one miejscom występowania granicy międzyfazowej γ′+γ / γ w stopach. Wyniki analiz termicznych zestawiono z wynikami innej metody zastosowanej przez autorów tj. kalorymetrycznej metody typu rozpuszczania.

The c-c 0 Co-based superalloys are newly developed class of refractory alloys which may replace commercial Ni-based superalloys owing to their favorable properties at high temperature. In case of new Co-based superalloys, the heat treatment aims to obtain microstructure composed of appropriate volume fraction of small cuboidal c 0 -Co 3 (Al,W) precipitates within the c-Co matrix. However, due to a high tendency to interdendritic segregations of alloying elements, the alloys based on Co-Al-W system should be normally homogenized before further steps of heat treatment (solutionizing and aging). In this study, thermal analysis was applied for determination of temperature range for primary heat treatment of the Co-9Al-9W (at.%). The differential thermal analysis (DTA) measurements were carried out on the thermal analyzer NETZSCH STA 449 F3 Jupiter. On the base of obtained results, respectively, solvus of c 0 phase and solidus temperatures were determined, as well as the thermal range of Co 3 W (DO 19 ) phase precipitation. As a consequence, the heat treatment without homogenizing (only solution and aging) was proposed as a most suitable way to obtain beneficial microstructure.

In this investigation, the thermal analysis of W-free cobalt-based superalloys based on Co–Al–Mo–Nb and Co–Ni–Al–Mo–Nb systems was performed. The analysis was performed at different stages of heat treatment process. The differential thermal analysis (DTA) was utilized for the determination of characteristic temperatures related to microstructural changes. First of all, the DTA analysis was carried out for discussing as-cast alloys in the temperature range of 40–1500 °C. The results showed thermal effects connected with melting and important order–disorder transition. The temperature range of 1200–1250 °C was chosen for performance of a first heat treatment operation for the investigated alloys. Specimens were annealed at selected temperature for 5 h. The microstructure of alloys after solution heat treatment was analyzed as well. Afterward, the solutionized specimens were subjected to the further thermal analysis in order to select the aging temperature according to the order–disorder transformation related to formation of γ′ phase with overall formula Co3(Al,X). Five aging variants were performed in the temperature range of 800–1000 with a step of 50 °C. After each stage of heat treatment, SEM/EDS analysis and hardness measurements were performed.

Electropolishing is electrochemical method used in metal working that has a vital role in production of medical apparatus, in food or electric industry. The purpose of this paper is to determine optimal current parameters and time required for conducting electropolishing process from the perspective of changes of surface microgeometry. Furthermore, effect of different types of mechanical working used before electropolishing on final surface state was evaluated by observation in changes of topography. Research was conducted on electrolytic copper and brass. Analysis of surface geometry and its parameters (Ra, Sa) was used as criterion describing efficiency of chemical electropolishing. Results of the experiment allow for current parameter optimization of electrochemical polishing process for selected non-ferrous alloys with preliminary mechanical preparation of the surface.

Technical copper alloys with tin are commonly named bronzes. Modern tin bronzes used in industry contain between 1 and 9 at.% of tin. Those alloys are used mostly for mechanical working. An increase in tin content in bronzes cooled in standard conditions results with appearance next to heterogeneous structure α and also other structures, including adverse phase δ. In ancient times, bronzes with tin content up to 14 at.% were used in order to manufacture ornaments or items used for everyday life such as singing bowl. An analysis of discussed bowl structure indicated dominant b 0 1 and c 0 1 martensite phase, which is an evidence of quenching in order to preserve the high-temperature β and γ phase structure. The main goal of this work was to obtain high-tin bronze structure corresponding to phases identified in singing bowl. On the basis of chemical composition and structural analysis of the singing bowl, a binary technical alloy was prepared by induction melting process. On such prepared alloy, a differential thermal analysis was performed in order to determine the presence of phase transitions. Based on results of thermal analysis, the temperature ranges and cooling conditions of heat treatment were investigated in order to perform structural analysis. Additionally, the structure of the alloy was analyzed in context to achieve a similar martensite phase as a matrix with α secondary phase.