Abstract
Following the findings regarding the surface stability of superalloys recently obtained by the authors, three Ni-based single crystal (SC) superalloys containing Re are designed with the aid of d-electrons concept. Creep-rupture, hot-corrosion and oxidation tests are conducted with the designed alloys in order to investigate experimentally their high temperature properties. The superalloy containing 5.4 mass% Re and 3.8 mass% Cr (A-1) shows an excellent combination of high temperature creep strength and hot corrosion resistance in comparison with a commercial second generation SC superalloy containing 3 mass% Re. The A1 alloy exhibits better creep rupture strength than the 3 mass% Re alloy under all the test conditions of 1313 K/137 MPa, 1 193 K/314 MPa, 248 MPa, 206 MPa and 1 123 K/441 MPa. Performance of the A-1 alloy is well comparable to the second generation alloy in the isothermal oxidation test but poor in the cyclic oxidation test. Another alloy (A-3) exhibits an excellent resistance to the cyclic oxidation test but its creep strength is not a level comparable to the second generation superalloy. Alloying balance is discussed for the excellent combination of high temperature creep rupture strength and good surface stability of superalloys.
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