Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Micrograph Library Full Record for Micrograph 726

Full Record for Micrograph 726

Link to full size image of micrograph 726
[261 KB]

View micrograph
.. in new window

View micrograph and record
.. in new window

You can also view and download the micrographs on Flickr
Micrograph no
Brief description
Ni-Superalloy, heat treated above gamma-prime solvus
heat treatment Link to MATTER Glossary entry for heat treatment, nickel
Metal or alloy
Ni, Cr 14.4-15.2, Co 13-18, Mo 3.5-4.5, Al 3.0-3.3, Ti 4.2-4.8, Ta 2.5, Zr 0.05-0.07, C 0.05, B 0.01-0.03 (wt%) (Ni-Superalloy)
Standard codes
Heat treated at 1200ºC for one hour, forced air cool.
Discs are used for high pressure and intermediate pressure turbine discs in Trent 800/900 series gas turbine engines.
Sample preparation
Ground to 4000 Grade SiC paper and then polished at 6 <span class="symbol">m</span>m 3 minutes, 1 <span class="symbol">m</span>m 5 minutes, Colloidal silica 10 minutes. Etched using a ‘Nimonic’ etch which preferentially attacks <span class="symbol">g</span>'.
Scanning electron microscopy (SEM) in backscattered electron imaging (BEI) mode
Length bar
10 μm
Further information
Micrograph shows a microstructure now devoid of g' as at this temperature it has become fully dissolved into the matrix. This results in grain growth, partly due to the solution of g' into the g matrix and also because the main mechanism for preventing grain growth, namely the primary g' is no longer present. Carbide phases still exist and act in places to inhibit grain boundary motion and therefore grain growth.

View schematic diagram of g' microstructure
R J Mitchell
Rolls-Royce University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge
Licence for re-use
Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales
Related micrographs