A metal alloy is for use at very high temperature, in particular the metal alloy can be used in a process for the manufacture of mineral wool by fiberizing a molten mineral composition. The metal alloy contains the following elements, the proportions being shown as percentage by weight of the alloy: Cr 20 to 35% Fe 10 to 25% W 2 to 10% Nb 0.5 to 2.5% Ti 0 to 1% C 0.2 to 1.2% Co less than 5% Si less than 0.9% Mn less than 0.9%
the remainder consisting of nickel and unavoidable impurities.

An object of the present invention is to provide an Ni-based alloy pipe or tube for nuclear power with reduced rate of SCC crack propagation. The Ni-based alloy pipe or tube for nuclear power according to the present invention is an Ni-based alloy pipe or tube having a wall thickness of 15 to 55 mm, having a chemical composition of, in mass %: 0.010 to 0.025% C; 0.10 to 0.50% Si; 0.01 to 0.50% Mn; up to 0.030% P; up to 0.002% S; 52.5 to 65.0% Ni; 20.0 to 35.0% Cr; 0.03 to 0.30% Mo; up to 0.018% Co; up to 0.015% Sn; 0.005 to 0.050% N; 0 to 0.300% Ti; 0 to 0.200% Nb; 0 to 0.300% Ta; 0% or more and less than 0.03% Zr; and the balance being Fe and impurities, wherein the Ni-based alloy pipe or tube has a microstructure being an austenite single phase, and the chemical composition satisfies the following equation, Eq. (1):
0.0020[N]/14{[Ti]/47.9+[Nb]/92.9+[Ta]/180.9+[Zr]/91.2}0.0015Eq. (1).
For the element symbols in Eq. (1), the contents of the corresponding elements in mass % are substituted.

An environmentally resistant alloy is disclosed having a transition metal that upon being included in the Ni Cr Al alloy causes no liquid phases below 1310 C., creates over 45% of a gamma phase above 900 C. up to 1310 C., creates over 30% comprised of a gamma prime phase between 450 C. and 600 C., and wherein the gamma prime phase is characterized by a formula (Ni,Co).sub.x(Cr,Al,Mo).sub.y wherein x and y are integers.

The present invention provides a heat-resistant alloy and a reaction tube having excellent oxidation resistance, excellent mechanical properties such as tensile ductility, and weldability. A heat-resistant alloy of the present invention comprises, in terms of % by mass, C: 0.35% to 0.7%, Si: more than 0% and 1.5% or less, Mn: more than 0% and 2.0% or less, Cr: 22.0% to 40.0%, Ni: 25.0% to 48.3%, Al: 1.5% to 4.5%, Ti: 0.01% to 0.6%, and the balance being Fe and inevitable impurities, wherein when Pa=11.1+28.1C+29.2Si0.25Ni45.6Ti, and Ya=13.75Al+63.75, Pa<Ya.

A refractory austenitic alloy suitable for use at temperatures greater than or equal to 1100? C., comprises the following elements in percent by weight: chromium between 25.0% and 32.0%, nickel between 50.0% and 61.0%, aluminum between 1.0% and 6.0%, niobium between 0.15% and 1.50%, carbon between 0.05 and 0.60%, one or more reactive elements in a total content of 0.060% or less, silicon at 0.30% or less, manganese at 0.30% or less, titanium at 0.40% or less, nitrogen at 0.20% or less, vanadium at 1.0% or less, iron between 4.0% and 18.0%, for balancing the elements of the alloy, zirconium, tungsten and sulfur being absent from the alloy, or in the form of impurities. The alloy also satisfies two criteria connecting the percentages by weight of at least some of the elements of the alloy.

A method for manufacturing a shaped body, comprising creating a mixture of a metal powder and binding agent, compacting the mixture to form a green compact, heating the green compact to a debinding start temperature T.sub.1, debinding the green compact by controlled heating of the green compact from start temperature T.sub.1 to end temperature T.sub.2 at a heat-up rate R.sub.1, presintering the debindered green compact to the presinter end temperature T.sub.VS at a heat-up rate R.sub.HVS, cooling the green compact from the presinter end temperature T.sub.VS at a cool-down rate R.sub.KVS, whereby at least the heat-up rate R.sub.HVS, the presinter end temperature T.sub.VS, and the cool-down rate R.sub.KVS are tuned relative to each other in such a way that the presintered green compact forming a blank has a surface porosity of 16% to 22% after presintering, and machining and sintering of the blank to form the shaped body.

A Ni-based alloy consisting of, in terms of mass %: 0.10%<C?0.30%; Si?0.50%; Mn?0.50%; P?0.030%; S?0.010%; Cu?3.00%; 30.0%?Cr?39.0%; Mo?3.00%; Fe?3.00%; 2.00%?Al?5.00%; O?0.0100%; N?0.050%; Nb?0.50%; V?0.50%; Ti?0.50%; Ta?0.50%; W?0.50%; and at least one selected from the group consisting of 0.0010%?B?0.0100%, 0.0010%?Mg?0.0100%, and 0.0010%?Ca?0.0100%, with the balance being Ni and unavoidable impurities, in which the alloy comprises an austenite phase having an average grain diameter of 50.0 ?m or less, a M.sub.23C.sub.6-type carbide having an average circle equivalent particle diameter of 1.0 ?m or more, and a massive ?-Cr phase having an average circle equivalent particle diameter of 10.0 ?m or less.

Reactor components formed using an erosion resistant alloy having desirable high temperature mechanical strength are provided. The erosion resistant components can include, but are not limited to, tubes, reactors walls, fittings, and/or other components having surfaces that can be exposed to a high temperature reaction environment in the presence of hydrocarbons and/or that can provide pressure containment functionality in processes for upgrading hydrocarbons in a high temperature reaction environment. The erosion resistant alloy used for forming the erosion resistant component can include 42.0 to 46.0 wt. % nickel; 32.1 to 35.2 wt. % chromium; 0.5 to 2.9 wt. % carbon; 0 to 2.0 wt. % titanium; 0 to 4.0 wt. % tungsten, and iron, with at least one of titanium and tungsten is present in an amount of 1.0 wt. % or more. The iron can correspond to the balance of the composition. Optionally, the erosion resistant alloy can provide further improved properties based on the presence of at least one strengthening mechanism within the alloy, such as a carbide strengthening mechanism, a solid solution strengthening mechanism, a gamma prime strengthening mechanism, or a combination thereof.

An object of the invention is to provide an alloy article that exhibits even better mechanical properties and/or even higher corrosion resistance than conventional high entropy articles without sacrificing the attractive properties thereof, a product formed of the alloy article, and a fluid machine having the product. An alloy article according to the invention has a predetermined chemical composition consisting of Co, Cr, Fe, Ni and Ti, Mo within a range of 1 atomic % or more and 5 atomic % or less, an element with a larger atomic radius than the atomic radiuses of Co, Cr, Fe and Ni within a range of more than 0 atomic % and 4 atomic % or less, and a balance of inevitable impurities.

Methods and compositions are provided for improving metal dusting corrosion, abrasion resistance and/or erosion resistance for various materials, preferably for applications relating to high-temperature reactors, including dense fluidized bed reactor components. In particular, cermets comprising (a) at least one ceramic phase selected from the group consisting of metal carbides, metal nitrides, metal borides, metal oxides, metal carbonitrides, and mixtures of thereof and (b) at least one metal alloy binder phase are provided. Ceramic phase materials include chromium carbide (Cr.sub.23C.sub.6). Metal alloy binder phase materials include ?-NiAl intermetallic alloys and Ni.sub.3Sn.sub.2 intermetallic alloys, as well as alloys that contain ?-Cr and/or ?-Ni.sub.3Al hard phases. Preferably, bimetallic materials are provided when the cermet compositions are applied using a laser, e.g., a laser cladding method such as high power direct diode (HPDD) laser, or by plasma-based methods such as plasma transfer arc (PTA) welding and powder plasma welding (PPW).