Creep behaviour and microstructure of Ni-Cr base alloys

AbstractThe creep behaviour of a series of alloys based on IN 597 (Nimonic 101) and with varying volume fractions of γ′ precipitate has been studied at 800°C in the standard condition of heat treatment and for two grain sizes. In order to assess the long-term structural stability of alloys of this type, which have high contents of Cr, creep tests were also carried out on material overaged for 5000 and 10000 h at 850°C. Optical and electron metallography have been used to examine the microstructural characteristics of the materials. The results show a consistent pattern of increasing creep resistance with increasing volume fraction of γ′ precipitate, although the effect was more significant in the coarse grained material. After overaging, the creep resistance and the life to rupture of the alloys were reduced, and acicular particles, believed to be γ′ phase, were observed in the microstructure. Some limitations of current mechanisms describing dislocation–particle interactions are discussed with respect to...

[1]  T. Gibbons.  The relation between “friction stress” and “flow stress” in a complex alloy with good creep resistance , 1978 .

[2]  A. Ardell,et al.  Precipitation hardening of Ni-12.19 at.% Al alloy single crystals , 1975 .

[3]  T. Gibbons.  Creep properties of Nimonic 90 in thin section , 1981 .

[4]  Y. Shimanuki.  Precipitation Hardening Mechanism in Ni-Base Wrought Superalloys , 1981 .

[5]  T. Gibbons,et al.  Ductility at high temperature and creep behaviour of directionally solidified Ni-Cr-base alloys , 1980 .

[6]  P. Hancock,et al.  Recrystallization of Nimonic 108 during Creep , 1975 .

[7]  J. Čadek,et al.  On stress dependence of strain rates due to grain boundary sliding and grain interior deformation in high-temperature creep of a Cu-30% Zn alloy , 1975 .

[8]  T. Gibbons,et al.  High-Temperature Ductility of Ni–20% Cr-Base Alloys , 1974 .

[9]  K. R. Williams,et al.  On the Stress- and Temperature-Dependence of Creep of Nimonic 80A , 1973 .

[10]  K. R. Williams,et al.  Stress-Change Experiments during High-Temperature Creep of Copper, Iron, and Zinc , 1973 .

[11]  T. Gibbons,et al.  The Influence of Grain Size and Certain Precipitate Parameters on the Creep Properties of Ni-Cr-Base Alloys , 1971 .

[12]  R. Lagneborg.  Deviations from Linearity in Creep-Rupture Curves , 1967 .

[13]  E. Hornbogen,et al.  Theorie der Wechselwirkung von Versetzungen mit kohärenten geordneten Zonen (I) , 1965 .

[14]  E. Hornbogen,et al.  Beobachtung der Wechselwirkung von Versetzungen mit kohärenten geordneten Zonen (II) , 1965 .