Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Andrzej Gradzik"

Wpływ doskonałości struktury monokryształów nadstopu niklu na ich wytrzymałość na pełzanie DOI:10.15199/24.2016.10.3


  Influence of crystal structure perfection of single crystal nickel-based superalloy on its creep resistance W artykule przedstawiono ocenę doskonałości struktury krystalicznej monokrystalicznego odlewu z nadstopu niklu CMSX-4 o strukturze mozaikowej. Do oceny doskonałości struktury przyjęto wartości kąta odchylenia αz - pomiędzy kierunkiem wyciągania odlewu i kierunkiem [001] oraz kąt dezorientacji αb - pomiędzy blokami mozaiki. Stwierdzono, że kąt odchylenia na powierzchni podłużnej odlewu, jak i na jego przekroju poprzecznym, przyjmuje wartości w zakresie 15,6-17,8° oraz 13,8-16,0° i 16,0-17,0°, natomiast kąt dezorientacji bloków mozaiki przyjmuje wartości w zakresie 1,08 - 1,35°. Próba pełzania wykonana dla fragmentów odlewu o różnych wartościach kątów αz i αb wykazała wpływ wartości kąta odchylenia kierunku [001] od kierunku wyciągania na odporność na pełzanie. The paper presents an analysis of crystal structure perfection of single crystal nickel-based superalloy CMSX-4 with blocky structure. Evaluation of crystalline structure was based on measurements of the value of αz angle - between the direction of crystallization and the direction [001] and αb angle - misorientation of the structure blocks. The measured values of αz on the cast surface was from 15.6 to 17.8° and from 13.8 to 16.0° and on the crosssection of cast in the range of 16.0-17.0°. The misorientation angle of blocky structure αb has a value from 1.08 to 1.35°. Creep resistance of single crystal was evaluated on specimens with various values of αz and αb. The influence of the value of angle αz and αb on the creep resistance of the single crystal was determined. Słowa kluczowe: orientacja krystaliczna, monokryształ, CMSX-4, pełzanie Key words: crystalline orientation, single crystal, CMSX-4, creep resistance Wprowadzenie. Nadstopy niklu w stanie lanym charakteryzuje występowanie w ich mikrostrukturze dwóch skład[...]

Analysis of precipitation strengthening process in 2xxx aluminium alloys DOI:10.15199/28.2016.3.2


  This paper is showing the results of study devoted to determination of the chemical composition and strengthening process parameters effect on the precipitation sequence of intermetallic phases in the supersaturated 2xxx aluminium alloys. This study was based on a calorimetric study where temperature’s effects were determined when precipitation process occurred during heating with different heating rate of the supersaturated alloys group of 2xxx. Based on the calorimetric curves and estimated values of ln(Q/T2) and 1000/RT an activation energy for precipitation and dissolution of phase components were evaluated. Key words: aluminium alloys, precipitation strengthening, calorimetry, activation energy. Inżynieria Materiałowa 3 (211) (2016) 104÷108 DOI 10.15199/28.2016.3.2 © Copyright SIGMA-NOT MATERIALS ENGINEERING 1. INTRODUCTION The 2xxx series of aluminium alloys generally contain 2 up to 10% copper, with smaller additions of other elements. The copper provides substantial increases in strength and facilitates precipitation hardening. The introduction of copper to aluminum can also reduce ductility and corrosion resistance [1, 2]. Thus, the most common applications for these type of alloys are aerospace and automotive industries. Due to both the development of new alloys, as well as the constantly increasing demands on their performance, there was a still need to examine the effect of chemical composition, kinetic of precipitation processes from supersaturated solutions and the influence of strengthening phases on the final mechanical properties of newly developed aluminium alloys. The mechanism of age hardening responsible for strengthening is based on the formation of intermetallic products through the decomposition of a metastable supersaturated solid solution SSS obtained by solution treatment and quenching. Since the interactions between the decomposition products and the dislocations are mainly responsible for the[...]

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