Guide for Use of Thermocouples in Creep and Stress-Rupture Testing to 1800F (1000C) in Air

The influence of certain trace elements, namely Pb, Sn, Te, Se and Tl, on the creep and stressrupture properties of Nimonic 105 was investigated at 815 °C. The work was supported by the Ministry of Defence, and was planned in close collaboration with Rolls-Royce, who advised, in particular, on the trace elements to be studied and the levels at which harmful effects on creep performance might be expected. The results obtained have confirmed that, with the exception of Sn, all the elements reduce the life to rupture and the ductility at failure when present in sufficient amount. The most deleterious impurities were Te and Pb. Stress-rupture testing with notched specimens gave a generally more sensitive indication of the presence of harmful amounts of impurity than did tests with plain specimens.

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Fine Microstructure of a Mechanically Alloyed Oxide Dispersion Strengthened Nickel-Base Superalloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079012 ◽

1977 ◽

Vol 35 ◽

pp. 298-299

Author(s):

Jordi Marti ◽

Timothy E. Howson ◽

David Kratz ◽

John K. Tien

Keyword(s):

Solid Solution ◽

Volume Fraction ◽

Stress Rupture ◽

Oxide Dispersion Strengthened ◽

Solid Solution Alloy ◽

Oxide Dispersion ◽

Creep And Stress Rupture ◽

Mechanically Alloyed ◽

Fine Microstructure ◽

Nickel Base

The previous paper briefly described the fine microstructure of a mechanically alloyed oxide dispersion strengthened nickel-base solid solution. This note examines the fine microstructure of another mechanically alloyed system. This alloy differs from the one described previously in that it is more generously endowed with coherent precipitate γ forming elements A1 and Ti and it contains a higher volume fraction of the finely dispersed Y2O3 oxide. An interesting question to answer in the comparative study of the creep and stress rupture of these two ODS systems is the role of the precipitate γ' in the mechanisms of creep and stress rupture in alloys already containing oxide dispersoids.The nominal chemical composition of this alloy is Ni - 20%Cr - 2.5%Ti - 1.5% A1 - 1.3%Y203 by weight. The system receives a three stage heat treatment-- the first designed to produce a coarse grain structure similar to the solid solution alloy but with a smaller grain aspect ratio of about ten.

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