Document Type : Original Article


1 Egyptian Armed Forces.

2 Professor, faculty of engineering, Cairo university, Giza, Egypt.


Nickel base Superalloys service at high temperatures, particularly in the hot zones of
gas turbine engine. These materials allow the turbine to operate more efficiently by
withstanding higher temperatures. Turbine Inlet Temperature (TIT) depends on the
temperature capability of first stage high-pressure turbine blade made of nickel base
superalloys exclusively.
Single crystal Nickel base turbine blade is free from g/ g¢ grain boundaries;
boundaries are easy diffusion paths and therefore reduce the resistance of the
material to creep deformation.
Experimental investigation carried out by using Different scrap of turbine blades with
different chemical compositions were melted aiming to control the chemical
composition of the product alloy, leading to a steel alloy called iron base superalloy
with nickel content (24.3%) and chromium content (13.2%) this new alloy has almost
the same mechanical properties of nickel base superalloy of higher price. This new
alloy can be used for production of turbine blades for small gas turbine engines less
than 200 KW. Solidification behavior of stepped cast specimen of nickel base
superalloy was studded by using three different cast thicknesses size. The results
and conclusion of this work show that the higher the cooling rate is the better the
mechanical properties. The results also show that the increase of cobalt and titanium
contents of nickel base alloy from 1.08 & 9.31 and 2.68 & 10.78 respectively leads to
an increase in ultimate tensile strength, yield strength and hardness. Microstructure
investigation of nickel base superalloys was conducted on all samples, the results
show the continuous matrix (g) and the primary strengthening phase (g¢), the
microstructure change from dendrite structure to a fine cellular one by increasing
titanium percent content.