A low-cost lightweight CO-based superalloy with cubic γ′ coherent strengthening and its preparation method

Abstract

The invention provides a low-cost lightweight Co-based superalloy with cubic γ′ coherent strengthening and a preparation method thereof, belonging to the field of Co-based superalloys, including Co, Ni, Al, Mo, Ti, Nb, Ta, Cr elements , the mass percent (wt.%) of its alloy composition is, Ni: 23.2-27.8, Al: 3.2-5.4, Mo: 8.4-11.6, Ti: 0.8-1.4, Nb: 0-2.5, Ta: 0-4.8, Cr: 2.5 to 3.0, Co: balance. The present invention realizes the coherent precipitation of cubic γ′ nanoparticles on the γ matrix through alloy composition design, and the γ′ nanoparticles can exist stably for a long time at 900°C, so that this type of alloy has excellent high-temperature mechanical properties and high-temperature resistance Oxidation and hot corrosion resistance; in addition, this series of alloys use Mo and a small amount of Ti, Nb, Ta to replace W, which effectively reduces the density and cost of the alloy, and the preparation process is simple. It is a good application in the aerospace field. Promising low-cost lightweight Co-based superalloys.

Description

technical field [0001] The invention belongs to the field of Co-based superalloys, in particular to a low-cost lightweight Co-based superalloy with cubic γ′ coherent strengthening, and its microstructure is cubic γ′-(Co / Ni) 3 (Al, Mo, Ti, Nb, Ta) nanoparticles are coherently precipitated on the face-centered cubic FCC-γ matrix, and the γ′ nanoparticles do not undergo obvious coarsening after long-term aging at 900°C, and have high high temperature structure stability properties, so that this type of alloy has excellent high-temperature mechanical properties, high-temperature oxidation resistance and hot corrosion resistance; at the same time, replacing W with Mo and a small amount of Ti, Nb, Ta effectively reduces the density and corrosion resistance of this series of alloys. cost. Background technique [0002] Due to its excellent mechanical properties and creep resistance at high temperatures, superalloys are used in the fields of aerospace engines and industrial gas turb...

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Problems solved by technology

However, with high temperature stable γ′-Ni 3 Unlike Al, the metastable γ′-Co 3 The (Al,W) phase is easily decomposed into FCC-γ, β-CoAl, and χ-Co during the aging process at a high temperature of 900 °C and above. 3 W and μ-Co 7 W 6 Stable phase, because the crystal structure of the precipitated phase changes, which will destroy the original γ / γ′ coherent relationship; and there is a large lattice distortion between these stable precipitated phases and the matrix, during the dislocation movement process It is easy to generate stress concentration, which induces crack initiation and deteriorates the mechanical properties of the alloy

At the same time, because the W content of the currently developed new Co-Al-W-based superalloy is 5-10 at.%, the alloy density is relatively high, generally higher than 9.0 g / cm 3 , such as Co-8.8Al-9.8W-2Ta (at.%) superalloy density up to 10.1g / cm 3

At present, the high density of new Co-based superalloys largely limits its application in the aerospace field.

In order to reduce the density of Co-based superalloys, a Co-Ni-Al-V-based superalloy was developed, but this type of alloy added a large amount of V elements, resulting in the γ / γ′ coherent structure in the alloy being higher than 850 It is difficult to exist stably at ℃, γ′-Co 3 (Al,V) decomposes to form hp-Co 3 The V lamellar structure seriously reduces the mechanical properties of the alloy, and at the same time, the cost of the alloy increases significantly due to the large amount of V added

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