Degradation of Creep Resistant Ni - Alloy During Aging at Elevated Temperature Part II: Structure Investigations

Journal title

Archives of Foundry Engineering




No 4

Publication authors


Ni-base superalloy ; structure ; SEM and TEM observations

Divisions of PAS

Nauki Techniczne


Archives of Foundry Engineering continues the publishing activity started by Foundry Commission of the Polish Academy of Sciences (PAN) in Katowice in 1978. The initiator of it was the first Chairman Professor Dr Eng. Wacław Sakwa – Corresponding Member of PAN, Honorary Doctor of Czestochowa University of Technology and Silesian University of Technology. This periodical first name was „Solidification of Metals and Alloys” , and made possible to publish the results of works achieved in the field of the Basic Problems Research Cooperation. The subject of publications was related to the title of the periodical and concerned widely understand problems of metals and alloys crystallization in a casting mold. In 1978-2000 the 44 issues have been published. Since 2001 the Foundry Commission has had patronage of the annually published “Archives of Foundry” and since 2007 quarterly published “Archives of Foundry Engineering”. Thematic scope includes scientific issues of foundry industry:

  • Theoretical Aspects of Casting Processes,
  • Innovative Foundry Technologies and Materials,
  • Foundry Processes Computer Aiding,
  • Mechanization, Automation and Robotics in Foundry,
  • Transport Systems in Foundry,
  • Castings Quality Management,
  • Environmental Protection.


The results of structure observations of Ni base superalloy subjected to long-term influence of high pressure hydrogen atmosphere at 750K

and 850K are presented. The structure investigation were carried out using conventional light-, scanning- (SEM) and transmission electron

microscopy (TEM). The results presented here are supplementary to the mechanical studies given in part I of this investigations. The

results of study concerning mechanical properties degradation and structure observations show that the differences in mechanical

properties of alloy subjected different temperature are caused by more advanced processes of structure degradation during long-term aging

at 850K, compare to that at 750K. Higher service temperature leads to formation of large precipitates of δ phase. The nucleation and

growth of needle- and/or plate-like, relative large delta precipitates proceed probably at expense strengthening γ" phases. Moreover, it can't

be excluded that the least stable γ" phase is replaced with more stable γ' precipitates. TEM observations have disclosed differences in

dislocation structure of alloy aged at 750K and 850K. The dislocation observed in alloy subjected to 750K are were seldom observed only,

while in that serviced at high stress and 850K dislocation array and dislocation cell structure was typical.


The Katowice Branch of the Polish Academy of Sciences


2015[2015.01.01 AD - 2015.12.31 AD]


Artykuły / Articles


ISSN 2299-2944