Patent ID: 6103186
Filing Date: 2000-08-15
Classification: B22F,B23K,C22C,C23C,F01D,Y10T

Abstract:
Method of making an article having an environmentally resistant, abradable surface, including:(a) Providing a powder mixture of first and second powdered alloys each having a base of elements M, Cr and Al in which M is at least one of the group of Ni, Co and Fe, the mixture having a total mixture composition of, by weight, 10-35% Cr, 4-19% Al, a small but effective amount of Y below about 0.1%, 2-6% Si and the balance M, and further characterized by a substantial absence of B,the first of the powdered alloys having a solidus and a liquidus, constituting from about 30 to about 50% by weight of the mixture, and comprising by weight 1.5-4% Al, 10-30% Cr and the balance M,the first alloy characterized by having silicon diffused thereinto in melting range lowering amount between about 5% and about 18% by weight,the second of the powdered alloys having a solidus and a liquidus, constituting from about 50 to about 70% by weight of the mixture, and having a melting range higher than the first of the powdered alloys,the second alloy characterized by a substantial absence of Si,the first and/or second alloy characterized by the presence of Y in an amount, up to a total of about 0.15% by weight, which will provide the Y content in the total mixture composition;(b) Compacting the mixture at compacting temperatures below the solidus of the first of the powdered alloys to provide a preform;(c) Disposing the preform on a surface of the article;(d) Heating the preform and article surface in a nonoxidizing atmosphere above the liquidus temperature of the first powdered alloy and below the liquidus of the second powdered alloy of the mixture; and(e) Holding the preform and article surface at the processing temperature for a time sufficient to liquid phase sinter the powder mixture, to interdiffuse elements of the first and second powders, and bond the preform to the article surface.