Ni-Co-Al-Cr-Fe series single crystal high-entropy high-temperature alloy and preparation method thereof

Abstract

The invention discloses a high-entropy high-temperature alloy and a preparation method thereof, and belongs to the field of high-entropy alloys. The alloy comprises the following chemical components of, in percentage by atom, 35%-40% of Ni, 30%-35% of Co, 10%-13% of Al, 5%-10% of Cr, 5%-8.5% of Fe, 1%-2.5% of Ti, 1%-3% of Ta, 0.01%-1% of Mo, 0.01%-1% of W, 0-1% of Re, 0.02%-0.12 % of C, 0.002%-0.015% of B, 0.005%-0.12% of Hf, and 0.05%-0.15% of RE, wherein Al+Ti+Ta is greater than or equal to 14% and less than or equal to 16%, and RE is any one rare earth element of Ce, La and Y. The preparation process of the alloy comprises the following steps of weighing and matching alloy elements according to the molar ratio, putting the alloy elements into a smelting furnace for smelting, carrying out high-temperature refining and casting to obtain an alloy ingot, preparing a (001) oriented single crystal high-entropy high-temperature alloy bar by adopting a high-speed solidification Bridgeman method, and then performing solution treatment and secondary aging treatment on the alloy bar. The prepared alloy bar has good high-temperature strength and thermal corrosion resistance, and is a candidate material of a hot-end part of an aero-engine and an industrial gas turbine.

Description

technical field [0001] The invention belongs to the field of high-entropy alloys, and relates to a Ni-Co-Al-Cr-Fe single-crystal high-entropy superalloy and a preparation method thereof. Background technique [0002] High-entropy alloy refers to a new type of alloy system that includes 5 or more components, and the atomic ratio of each component is equal or nearly equal. Judging from the size of the mixing entropy, high-entropy alloys generally satisfy the mixing entropy ΔS mix >1.5R (R is the gas constant) requirement (mixing entropy is calculated according to the formula In the formula, i represents any element in the alloy, N is the sum of all elements in the alloy, c i is the mole fraction of element i). High-entropy alloys generally form solid solutions, which have structural lattice distortion effects, kinetic hysteresis diffusion effects, and performance cocktail effects. It is easy to obtain solid solution phases, nanostructures, and even amorphous structures ...

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Problems solved by technology

For example, FeCoNiCrMn high-entropy alloys with excellent low-temperature fracture toughness have too low strength at room temperature and high temperature to meet the requirements of practical engineering applications; TaNbMoWV and TaNbMoW alloys with strengths much higher than nickel-based superalloys at high temperatures Density and raw material prices, poor oxidation resistance, also seriously hinder its high-temperature application; AlCoCrFeNi high-entropy alloys with high room temperature hardness show brittleness when stretched at room temperature, etc.

In addition, the current research on high-entropy alloys for engineering structures is mainly focused on their mechanical properties at room temperature, and there is little exploration of their application potential in high-temperature mechanical properties.

Therefore, in view of the common problems of insufficient high-temperature strengthening ability, high brittleness and poor oxidation resistance of existing high-entropy alloys, the mechanical properties of the alloy are further improved by strengthening methods such as solid solution strengthening and precipitation strengthening, and the composition optimization is used to improve the resistance of the alloy. Oxidation properties, etc., are the problems that need to be solved urgently in the application of high-entropy alloys in the field of high-temperature structural materials.

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