Granulometric and gradient hard alloy prepared by using liquid-phase infiltration method and preparation method thereof

The invention discloses a granulometric and gradient hard alloy prepared by using a liquid-phase infiltration method and a preparation method thereof; and, by optimizing the attachment manner of a grain inhibitor on the surface of a green body and changing the disperse manner of the grain inhibitor, high-temperature disperse sintering and time are optimized, so that the granulometric and gradient alloy with the gradient layer of being more than or equal to 0.2 mm and the maximal thickness of being more than 6 mm can be prepared. The method disclosed by the invention is simple in process, low in equipment investment, easy to control the process and low in production cost; the thickness of the granulometric and gradient layer of the WC-Co granulometric and gradient hard alloy prepared by using the method is more than or equal to 0.2 mm; the maximal thickness of the WC-Co granulometric and gradient hard alloy is more than 6 mm; the average size of WC grains in the core is about 1.05-1.5 times of that of WC grains in the surface layer; the Hv1 hardness of the surface layer is about 1.03-1.2 times of that of the core; furthermore, the alloy does not have Co gradient change; because of having smaller WC grains, the surface layer has higher hardness and abrasive resistance; because of having larger WC grains, the core has better toughness; in addition, because of having enough machining allowance, the alloy can be applied in various products more easily.