CHAPTER 1
INTRODUCTION
No single factor in jet engine design has been as
important as the development of high strength, high
temperature alloys for the hot turbine section of the
engine. This development has proceeded over the
relatively short period from the early 1930's, the early
development days of the jet engine, to the present. These
high strength, high temperature alloys had to maintain
their strength at very high temperatures under very high
load conditions yet still maintain close dimensional
tolerances so that thrust levels would not deteriorate
significantly with time. They had to be capable of
withstanding extremes in thermal cycling and had to resist
degradation under the most severe of hot corrosion
environments. It is no wonder these materials were and
are referred to as superalloys.
Alloy development has proceeded in superalloy systems
as it has historically proceeded in other metallurgical
systems -- empirical trial and test. In this approach
numerous alloys are prepared, fabricated, heat treated,
and tested. The winners are selected based on their
property responses. Compositional tolerances are
determined based again on desirable property limits.
1