3. metallurgy method
Powder metallurgy method, chiefly accustomed manufacture precipitation reinforced and compound dispersion reinforced superalloys. This method permits for malleability and even superplasticity of solid superalloys that ar typically indeformable.
4, strength improvement method
(1) primary solid solution strengthening
Adding parts completely different within the size of the bottom metal atom (chromium, tungsten, molybdenum, etc.) causes distortion of the matrix metal lattice, adding parts that scale back the stacking fault energy of the alloy matrix (such as cobalt) and adding will weigh down the diffusion rate of the matrix parts. parts (tungsten, molybdenum, etc.) to strengthen the matrix.
(2) Precipitation strengthening
By aging treatment, the second phase (γ', γ", carbide, etc.) is precipitated from the concentrated primary solid solution to strengthen the alloy. The γ' phase is the same as the matrix, and may be a face-centered boxy structure, and also the lattice constant is analogous to the matrix. And coherent with the crystal, so the γ phase can be uniformly precipitated in the form of fine particles in the matrix, clogging the dislocation motion, and manufacturing vital strengthening result. The γ' phase is an A3B type intermetallic compound, A represents nickel, cobalt, and B represents atomic number 13, titanium, niobium, tantalum, vanadium, tungsten, and metal, molybdenum, iron are often either A or B. The typical γ' phase in Ni-based alloys is Ni3 (Al, Ti). The strengthening effect of γ' phase It can be enhanced by:
1 increase the number of γ' phases;
2 having a suitable degree of mismatch between the γ' phase and the matrix to obtain a strengthening effect of coherent distortion;
3 adding elements such as yttrium and lanthanum to increase the antiphase boundary energy of the γ' phase to improve its ability to resist dislocation cutting;
4 Adding parts adore atomic number 27, tungsten, molybdenum and the like to increase the strength of the γ phase. The γ" phase is a body-centered tetragonal structure, and its composition is Ni3Nb. Because of the large mismatch between the γ" phase and the matrix, an oversized degree of coherent distortion are often caused, and also the alloy obtains a high yield strength. However, once it exceeds 700 ° C, the strengthening result is considerably reduced. Cobalt-based superalloys typically don't contain a gamma section however ar strengthened with carbides.