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Experimental confirmation of high-temperature phase boundaries in the nickel-rich part of Ni-Al-Cr system

Maciąg T., Migas D., Płachta A.

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e203, 2022

EN

Precise determination of the course of phase boundaries is particularly important for alloys operating at elevated temperatures. In the case of multi-component materials such as nickel superalloys, computational methods are often used for this purpose. They are based on binary and ternary systems and require reliable experimental data. Commonly used research methods for determining phase boundaries at elevated temperature have a number of limitations and it is difficult to interpret their results without the support of other studies. This work presents a series of experiments to confirm the course of phase boundaries γ′/(γ′ + γ) and (γ′ + γ)/γ in Ni-Al-Cr system, particularly at 600 °C. For this purpose, a series of alloys from Ni-rich part of Ni–Al-Cr ternary system was prepared by vacuum induction melting (VIM) and casting into graphite mold under an argon protective atmosphere. Samples after machining were subjected to compression tests using the Gleeble 3800 thermomechanical simulator at room temperature as well as directly at 600 °C after pre-heating at 1100 °C. Stress–strain curves of various character were obtained and were associated with the appropriate phase structure confirmed by X-ray diffraction (XRD) analysis. The relationship between the phase structure of the studied alloys and their mechanical properties has been proven. Compression results were compared with the results of hardness measurements, high-temperature calorimetric solution method and differential thermal analysis (DTA). The obtained results showed a very good agreement in terms of the course of the γ′/(γ′ + γ) and (γ′ + γ)/γ phase boundary in Ni-Al-Cr system.

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DTA Thermal Analysis of Alloys from Nickel-Rich Part of Ni-Al-Cr System

Maciąg T.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

981--986

EN

Thermal analysis allows for determination of temperature specific for the beginning and the end of phase transitions occurring in studied samples. In this paper results obtained from DTA (Differential Thermal Analysis) of alloys of chemical composition referring to nickel-rich part of Ni-Al-Cr system, specifically from section Ni75Al25÷Ni65Cr35 are presented. Those alloys are based on intermetallic phase Ni3 Al. Referring to measurements obtained during heating and cooling, characteristic peaks related to occurrence of phase transition of order-disorder type were noted as well as melting and solidification temperature of alloys was determined. Results of thermal analysis DTA of studied range were compared with results obtained for section Ni75Al25÷Ni75Cr25 and Ni75Al25÷Ni87Cr13, additionally results of measurements performed on high-temperature solution calorimeter were collated. Both methods presented good compatibility.

3

DSC Analysis of Order–Disorder Transition in Ni3Al Based Alloys From Ni-Al-Cr System

Maciąg T., Rzyman K., Przeliorz R.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3A

1871--1876

EN

Ni-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.

PL

Układ 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.