Uwe Glatzel

Summary: Different Strengthening
MMechanisms h i in i Ni-Base Ni B SSuperalloys ll
• It Internal lb back kstress: t σ i = α ⋅ G ⋅ b b⋅
~ 250 MPa ≈ σexternal • Orowan stress:
~ 500 MPa (reduced by coarsening)
• Solid solution strengthening (e.g. by Re):
~110MPa(short range ~1/r2 ~ 110 MPa (short range ~ 1/r )
σ
ρ
Orowan
σ
G ⋅b
≈
L
i
solid solution
• Coherent γ' precipitates: σ coherency ≈ δ ⋅ E
~ -200 MPa (compression, reduced by semi-coherency)
≈
Ω − Ω
Ω
i ci With α =1, G = 100 GPa ≈ E, b = 250 pm, ρ = 1014 m-2 , , p , ρ , L = 50 nm, , c Re = 1 at.%, ,
, δ = -2⋅10-3 Ω
− ΩNi
Re =
Ω
Ni
0.
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University Bayreuth Uwe Glatzel, Metals and Alloys
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E