الفهرس 
Chapter 1 : IntroductionOnly 14 pages are availabe for public view
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Abstract
The Creep behaviour of high temmperture materials especially nickel base single crystal alloy srr99 has been studied ied in the temperatures of 850 and 950 C and at engineering stresses of 200 to 650 Mpa with step of 50 Mpa for diffexent heat treatments. Various heat treatments ( HTL, HT2, HT3, HT4, HT5, and HT6. were used to produce a wids range of initial- phase sizes.
above the following peramters were In the present work the temperature and stress ranges used as mentioned above the following paramters were studied to determine the creep properties: steady state creep rate time to fracture time at L& strain incubation time ductillty( elongation and reduction of area .and larson- miller parameter. Internal back stress at 850 c for different stress levels in the rang from 400 to 650 Mpa and different heat treatments. Hot hardness test has been investlgated furthermore the morphology of – phase as a function of stress and temperature has also been hnvestigated.
The obtained results show that the optimum creep properties ara achieved when rafting of phase zize reaches a maximium value. It was found that the phase size lead to optimum creep strength internia back stress and hot hardness results is currently found to by 0.38 um, HT6. on the other hand by increasing or decreasing of the – phase size the creep properties decreases.