A hard composite composition may comprise a binder and a polymodal blend of matrix powder. The polymodal blend of matrix powder may have at least one first local maxima at a particle size of about 0.5 nm to about 30 m, at least one second local maxima at a particle size of about 200 m to about 10 mm, and at least one local minima between a particle size of about 30 m to about 200 m that has a value that is less than the first local maxima.

The present disclosure concerns composite material having improved strength at elevated temperatures. The composite material comprises a matrix of an aluminum alloy (comprising, in weight percent, Si 0.05-0.30, Fe 0.04-0.6, Mn 0.80-1.50, Mg 0.80-1.50 and the balance being aluminum and unavoidable impurities) as well as particles of a filler material dispersed within the matrix. The matrix can optionally comprise Cu and/or Mo. In some embodiments, the composite material comprises, as a filler material, B.sub.4C as well as an additive selected from the group consisting of Ti, Cr, V, Nb, Zr, Sr, Sc and any combination thereof. The present disclosure also provides processes for making such composite materials.

Turbine buckets include a pressure side, a suction side opposite the pressure side, and a bucket squealer tip attached to the pressure side and the suction side. The bucket squealer tip includes a plurality of high hot hardness shroud-cutting deposits deposited on its exterior surface that have a hardness of at least about 1100 kg mm.sup.2 and a melting temperature of at least about 1500 C.

The invention relates to vertical or inclined electrodes of an electrolyzer for electrolytically producing aluminum from aluminum oxide. An electrode contains an electrode base and a surface coating based on refractory ceramics. According to a first variant of the invention, the electrode base is made of a composite material containing between 5% and 90% by mass of refractory ceramics, and of at least one metal having a melting temperature exceeding 1000 C., which forms refractory intermetallic compounds upon interaction with aluminum, and/or containing at least one alloy of such a metal. According to a second variant of the invention, the electrode base is made of a metal alloy, for example structural steel or another alloy, and the surface of the electrode base has applied thereto an intermediary layer consisting of a composite material having the composition described above.

A composite material combininga precious metal or an alloy containing a precious metaland a boron-based ceramic having a melting point greater than that of said precious metal and a density at most equal to 4 g/cm3.

The invention is a process for manufacturing a nano aluminum/alumina metal matrix composite and composition produced therefrom. The process is characterized by providing an aluminum powder having a natural oxide formation layer and an aluminum oxide content between about 0.1 and about 4.5 wt. % and a specific surface area of from about 0.3 and about 5 m.sup.2/g, hot working the aluminum powder, and forming a superfine grained matrix aluminum alloy. Simultaneously there is formed in situ a substantially uniform distribution of nano particles of alumina. The alloy has a substantially linear property/temperature profile, such that physical properties such as strength are substantially maintained even at temperatures of 250 C. and above.

The invention is a process for manufacturing a nano aluminum/alumina metal matrix composite and composition produced therefrom The process is characterized by providing an aluminum powder having a natural oxide formation layer and an aluminum oxide content between about 0.1 and about 4.5 wt. % and a specific surface area of from about 0.3 and about 5 m.sup.2/g, hot working the aluminum powder, and forming a superfine grained matrix aluminum alloy. Simultaneously there is formed in situ a substantially uniform distribution of nano particles of alumina. The alloy has a substantially linear property/temperature profile, such that physical properties such as strength are substantially maintained even at temperatures of 250 C. and above.

An aluminum-based composite material includes a plurality of coarse crystalline grains (3) of pure aluminum, and a plurality of fine crystalline grains (4) each having an aluminum matrix (1), and a dispersion material (2) dispersed inside the aluminum matrix and formed by reacting a portion or all of an additive with aluminum in the aluminum matrix. The fine crystalline grains exist among the coarse crystalline grains, and the fine crystalline grains have crystalline grain diameters smaller than crystalline grain diameters of the coarse crystalline grains.

The invention is a process for manufacturing a nano aluminum/alumina metal matrix composite and composition produced therefrom. The process is characterized by providing an aluminum powder having a natural oxide formation layer and an aluminum oxide content between about 0.1 and about 4.5 wt. % and a specific surface area of from about 0.3 and about 5 m.sup.2/g, hot working the aluminum powder, and forming a superfine grained matrix aluminum alloy. Simultaneously there is formed in situ a substantially uniform distribution of nano particles of alumina. The alloy has a substantially linear property/temperature profile, such that physical properties such as strength are substantially maintained even at temperatures of 250 C. and above.

Described herein are methods of forming a neutron shielding material. Such material may comprise a powder blend comprising a first component comprising a blend of a first metal particle and a first ceramic particle; and a second component comprising a reinforcing chip, the reinforcing chip comprising a second ceramic particle dispersed within a chip metal matrix.