The present disclosure discloses a preparation method of a powder metallurgy (PM) superalloy with high strength and plasticity. Under the multi-field coupling action of a thermal field and a force field, the PM superalloy is obtained in a high-temperature graphite mold by using the method of conducting heat preservation and oscillating-pressure sintering in two steps. Under the action of a circulating pressure, rearrangement of powders and discharge of pores are promoted, and therefore, the PM superalloy is sintered and formed. The present disclosure further discloses a PM superalloy prepared by using the method above. The PM superalloy has the characteristics of low grade of prior particle boundary defects, uniform grain refinement and high density. The sintered PM superalloy obtained in the present disclosure has a yield strength of 955 MPa, a tensile strength of 1,437 MPa and an elongation of 31.9%, and has high strength and plasticity.

A nickel-based brazing foil with a composition consisting essentially of 11 atom %<Cr≤16 atom %, 0 atom %≤Mo≤3.5 atom %, 4 atom %≤B≤5.5 atom %, 11 atom %≤Si≤16 atom %, 0 atom %≤P≤0.5 atom %, 0 atom %≤C≤0.85 atom %, 0 atom %≤Fe≤5 atom %, 0 atom %≤Co≤5 atom %, 0 atom %≤Cu≤2 atom %, 0 atom %≤V≤2 atom %, 0 atom %≤Nb≤2 atom %, incidental impurities of ≤1.0 wt. % and the rest Ni, is provided.

This application relates to a nickel-based superalloy suitable for additive manufacturing and a method for manufacturing a high-temperature member using the same. The nickel-based superalloy includes 13.7% to 14.3% by weight of Cr, 9.0% to 10.0% by weight of Co, 3.7% to 4.3% by weight of Mo, 2.6% to 3.4% by weight of Ti, 3.7% to 4.3% by weight of W, 2.6% to 3.4% by weight of Al, 0.15% to 0.19% by weight of C, greater than 0% by weight and not less than 0.005% by weight of B, 0.01% to 0.05% by weight of Zr, 2.0% to 2.7% by weight of Ta, 0.6% to 1.1% by weight of Hf, Ni residue, and unavoidable impurities. The nickel-based superalloy has a high fraction of strengthening phase, thereby maintaining excellent high-temperature strength. Additive manufacturing with the nick-based superalloy is much easier than existing nickel-based superalloys, thereby cost-effectively providing maximized cooling efficiency.

A Nickel-based superalloy, whose composition includes, in percent by weight of the total composition: Chromium: 10.0-11.25; Cobalt: 11.2-13.7; Molybdenum: 3.1-3.8; Tungsten: 3.1-3.8; Aluminium: 2.9-3.5; Titanium: 4.6-5.6; Niobium: 1.9-2.3; Hafnium: 0.25-0.35; Zirconium: 0.040-0.060; Carbon: 0.010-0.030; Boron: 0.01-0.030; Nickel: remainder as well as unavoidable impurities; the composition being free of tantalum.

Provided is a Ni-based alloy having a composition consisting of, by mass %, Cr: 14.0% to 17.0% (preferably, not less than 14.0% and less than 15.0%), Fe: 5.0% to 9.0%, Ti: 2.2% to 2.8%, Al: 0.40% to 1.00%, a total amount of Nb+Ta: 0.7% to 1.2%, B: 0.001% to 0.010%, Zr: 0.01% to 0.15%, Mg: 0.001% to 0.050%, Mn: 0.01% to 0.20%, Cu: 0.005% to 0.300%, Mo: 0.01% to 0.30%, C: 0.01% to 0.05%, and the balance of Ni with inevitable impurities. In a creep test under conditions of a test temperature of 750° C. and a test load of 330 MPa, the Ni-based alloy preferably has a creep rupture life of not less than 120 hours and an elongation of not less than 16%, i.e., has good high-temperature creep characteristics. The Ni-based alloy is suitable for a gas turbine member.

A method for preparing an improved article including a nickel-based superalloy is presented. The method includes heat-treating a workpiece including a nickel-based superalloy at a temperature above the gamma-prime solvus temperature of the nickel-based superalloy and cooling the heat-treated workpiece with a cooling rate less than 50 degrees Fahrenheit/minute from the temperature above the gamma-prime solvus temperature of the nickel-based superalloy so as to obtain a cooled workpiece. The cooled workpiece includes a coprecipitate of a gamma-prime phase and a gamma-double-prime phase, wherein the gamma-prime phase of the coprecipitate has an average particle size less than 250 nanometers. An article having a minimum dimension greater than 6 inches is also presented. The article includes a material having a coprecipitate of a gamma-prime phase and a gamma-double-prime phase, wherein the gamma-prime phase of the coprecipitate has an average particle size less than 250 nanometers.

A method for preparing an article including a nickel-based superalloy is presented. The method includes heat-treating a workpiece including a nickel-based superalloy at a temperature above a gamma-prime solvus temperature of the nickel-based superalloy and cooling the heat-treated workpiece with a cooling rate less than 50 degrees Fahrenheit/minute from the temperature above the gamma-prime solvus temperature of the nickel-based superalloy so as to obtain a cooled workpiece. The cooled workpiece includes a gamma-prime precipitate phase having an average particle size less than 250 nanometers at a concentration of at least 10 percent by volume, and is substantially free of a gamma-double-prime phase. An article having a minimum dimension greater than 6 inches is also presented. The article includes a material that has a gamma-prime precipitate phase having an average particle size less than 250 nanometers, and is substantially free of a gamma-double-prime phase.

A method of metallurgical processing includes, providing a workpiece that has been formed by additive manufacturing of a nickel-chromium based superalloy. The workpiece has an internal porosity and a microstructure with a columnar grain structure and delta phase. The workpiece is then hot isostatically pressed to reduce the internal porosity and to at least partially retain the columnar grain structure and the delta phase. The workpiece is then heat treated to at least partially retain the columnar grain structure and the delta phase.

A nickel-chromium-iron-aluminum alloy contains (in wt. %)>17 to 33% chromium, 1.8 to <4.0% aluminum, 0.10 to 15.0% iron, 0.001 to 0.50% silicon, 0.001 to 2.0% manganese, 0.00 to 0.60% titanium, 0.0002 to 0.05% each of magnesium and/or calcium, 0.005 to 0.12% carbon, 0.001 to 0.050% nitrogen, 0.0001 to 0.020% oxygen, 0.001 to 0.030% phosphorus, not more than 0.010% sulfur, not more than 2.0% molybdenum, not more than 2.0% tungsten, the remainder nickel with nickel ≥50% and the usual process-related impurities, for use in solar power tower plants using nitrate salt melts as the heat transfer medium, wherein the following relations must be satisfied: Fp≤39.9 (2a) with Fp=Cr+0.272*Fe+2.36*Al+2.22*Si+2.48*Ti+0.374*Mo+0.538*W−11.8*C (3a), wherein Cr, Fe, Al, Si, Ti, Mo, W and C is the concentration of the respective elements in % by weight.

Provided is a method for manufacturing an Ni-based alloy member in which the equilibrium amount of γ′ phase precipitation at 700° C. is from 30 to 70 volume %. The method includes the steps of preparing an Ni-based alloy powder having a predetermined chemical composition; forming a precursor body wherein an average grain diameter of the γ phase grains is 50 μm or less, by using the Ni-based alloy powder; and heating the precursor body to a temperature at least the γ′ phase solvus temperature and subsequently slow-cooling the heated precursor body from the temperature to a temperature at least 100° C. lower than the γ′ phase solvus temperature at a cooling rate of 100° C./h or lower. There is obtained a softened body in that the γ′ phase particles of at least 20 volume % precipitate between/among the γ phase grains having an average grain diameter of 50 μm or less.