A γ' phase strengthened cobalt-based superalloy and its preparation method

Abstract

The invention discloses gamma'-phase intensified cobalt-based superalloy and a preparation method thereof, and belongs to the field of superalloy. The gamma'-phase intensified cobalt-based superalloyis prepared from the following alloy chemical components in percentage by weight: 3 to 6 percent of Al, 6 to 20 percent of W, 2 to 6 percent of Ti, 2 to 6 percent of Ta, 18 to 38 percent of Ni, 0 to 10 percent of Cr, 0 to 5 percent of Mo, 0 to 2 percent of Nb, 0 to 2 percent of Si and the balance of Co. The preparation method is characterized by melting by adopting a vacuum arc furnace, carrying out solid solution heat treatment at 1250 to 1300 DEG C, and carrying out aging heat treatment at 900 to 1150 DEG C. The gamma'-phase intensified cobalt-based superalloy disclosed by the invention is intensified by a gamma' phase having an L12 crystal structure and has a cubic shape, the volume fraction is greater than 65 percent, and the gamma'-phase intensified cobalt-based superalloy is uniformly distributed in a gamma matrix having an A1 crystal structure. A Gamma / gamma' two-phase structure of the gamma'-phase intensified cobalt-based superalloy disclosed by the invention stably exists at 900 to 1150 DEG C, no secondary phase is separated out, and the gamma'-phase intensified cobalt-based superalloy is a candidate material for hot end components of an aircraft engine and an industrial gas turbine.

Description

technical field [0001] The invention belongs to the technical field of high-temperature alloys, and relates to a γ' phase-strengthened cobalt-based high-temperature alloy and a preparation method thereof. Background technique [0002] Due to its excellent high temperature strength, good oxidation resistance and hot corrosion resistance, superalloys have become irreplaceable key materials for the hot end parts of aero-engines and industrial gas turbines. Among them, cobalt-based superalloys were first used in the hot end parts of gas turbines from the 1930s to the 1950s. Compared with nickel-based superalloys, they have a higher melting point, better resistance to thermal corrosion, and thermal fatigue and solderability. However, due to the lack of L1 in traditional cobalt-based superalloys 2 Type γ' phase strengthening mechanism, high temperature strength and temperature bearing capacity are significantly lower than the nickel-based superalloy strengthened by γ' phase, and...

AI Technical Summary

Problems solved by technology

However, most of the existing Co-Al-W-based alloys have a γ' phase dissolution temperature lower than 1150°C, and only a few reports are higher than this value, such as Feng Qiang et al. (Chinese Patent, Patent No. ZL201310018243. Stable γ' phase strengthened cobalt-based superalloy and its preparation method ") published at 1184 ° C

Moreover, the existing Co-Al-W-based alloys tend to precipitate harmful secondary phases at high temperatures, and it is difficult to form a stable γ / γ’ two-phase structure above 1150 °C.

However, the dissolution temperature of the γ' phase of advanced nickel-based single crystal superalloys has exceeded 1300 °C, which indicates that the temperature bearing capacity of new cobalt-based superalloys is still far behind that of nickel-based superalloys

On the other hand, most existing Co-Al-W-based alloys have densities higher than 9.3 g cm -3 , higher than that of advanced nickel-based superalloys (7.9~9.2gcm -3 ), limiting the application of new cobalt-based superalloys in engines

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