Page 86 - Policy Commission - SecuringTechnology - Critical Metals for Britain

86 PRIMARY MATERIALS
AEROENGINE MATERIALS
Since its earliest development the the the performance of of the the the aero gas turbine has always been limited by the the the capability of of available materials This is is particularly true in in the the the high-temperature sections of the the the engine: the the the high high pressure (HP) compressor combustor and turbine (see figure 80) Here the the the the peak temperature and and pressure attainable and and hence the the the the thermo-dynamic efficiency of the the the the cycle is limited by the the the temperature capability of the the the alloys used Improvements in performance fuel efficiency and emissions are therefore only possible through the use use of advanced high-temperature materials materials systems The materials materials used must combine temperature temperature capability with the highest levels of mechanical integrity and and resistance to corrosion and and oxidation HP Compressor
Combustor
HP Turbine
Figure 80: A cross-section of of a a a a modern gas-turbine engine engine indicating key engine engine components of of relevance to this section section ALLOY
U720
IN718
CMSX-4 Bal Bal Bal 18
19
6 5
15
9
3
3
0 6 1 3
6 3
2 5
0 5
5
6 5
0 0 9
1 6 5
5
1 0 1 18
5
0 0 035
0 0 04
0 0 033
0 0 03 Ni Cr Co Mo W Re Al Ti Ta Nb Hf Fe C C C B Zr
Figure 81: Table shows the the typical composition of the the commonly used disc alloys IN718
and and U720
and and blade alloy alloy CMSX4 (in wt%)