A kind of preparation method of hard alloy resistant to high temperature softening

Abstract

The invention discloses a method for preparing hard alloy capable of resisting high temperature softening. The method is characterized by including the steps that an Al-Ni(OH)2 binding phase with Al partially replacing Ni and a composite hard phase with Ni(OH)2 coating WC are prepared at first; the Al-Ni(OH)2 binding phase and the composite hard phase are subjected to ball milling, filtering, drying and other procedures for compression molding after being mixed; and finally, two-stage atmosphere sintering is performed, namely, the Al-Ni(OH)2 binding phase is converted into Al-Ni in the Ar / H2 atmosphere and at a low temperature, and the coating layer Ni(OH)2 is converted into Ni; and vacuum sintering is performed at a high temperature, so that the Al-Ni and the Ni react for in-situ generation of Ni3Al, and the hard alloy capable of resisting high temperature softening is obtained. By the adoption of the method, the problems that the Al is prone to oxidation, breaking and homogeneous dispersion are difficult, volatilization losses can be caused easily, and pores are likely to be formed in sintering mobility in the prior art are solved; the Ni3Al phase can be formed in an in-situ mode in the sintering process; and moreover, uniform distribution around the hard phase is realized, and the hard alloy prepared through the method can be used for manufacturing cutting tools and oxidation-resisting parts.

Description

Technical field [0001] The invention relates to a method for preparing a hard alloy, in particular to a method for preparing a hard alloy resistant to high temperature softening, and belongs to the field of composite materials. Background technique [0002] At present, with the development of cutting in the direction of high-speed cutting and the continuous emergence of difficult-to-machine materials, the requirements for high-temperature mechanical properties of tools at cutting temperatures are getting higher and higher. It is an effective method to use intermetallic compounds as the cemented carbide binder phase to improve its high temperature strength, hardness and oxidation resistance. ZL201110086038.1 invented a nickel-aluminum intermetallic compound Ni 3 Al is a cemented carbide with binder phase, in which B is 0.0025~0.0252wt%, and the volume percentage of binder phase is 10%~40%; its preparation includes: according to the composition ratio of Ni50Al, 2.09~28.94wt% nickel...

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Problems solved by technology

[0004] The present invention aims at the present preparation of high temperature softening resistant hard alloy materials by using mixed ball milling and sintering of Ni and Al metal powders to form NiAl, which is then mixed with Ni and ball milled to form Ni in the sintering process. 3 The method of Al has the disadvantages that Al powder is easily oxidized during the ball milling process, Al powder is plastically deformed into flakes, and it is difficult to break and disperse. After prefabricating NiAl, the crushing process is complicated, the particle size control of the broken NiAl intermetallic compound and subsequent ball milling Due to the difficulty of uniform dispersion control and other problems, it is proposed to use Al-Ni(OH) which partially replaces Ni with Al first. 2 Binder phase and Ni(OH) 2 Composite hard phase coated with WC, after mixing the two, go through ball milling, filtering, drying and other processes, then press molding, and finally carry out two-stage atmosphere sintering, that is, Ar / H at low temperature 2 Al-Ni(OH) in atmosphere 2 The binder phase transforms into Al-Ni, and the cladding layer Ni(OH) 2 Converted to Ni; Vacuum sintering at high temperature makes Al-Ni react with Ni to form Ni-containing Ni in situ 3 Al, to obtain hard alloys resistant to high temperature softening

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