Powder metallurgy materials

Flat tensile creep specimens were machined from the blocks so that the longitudinal specimen axes were either parallel to the plane containing the majority of the long axes of the fibres for the squeeze-cast composites or parallel to the extrusion direction for powder metallurgy materials. Constant stress tensile creep tests were carried out at temperatures from 423 to 523 K. The applied stresses ranged from 10 to 200 MPa. Creep tests were performed in purified argon in tensile creep testing machines with the nominal stress maintained constant to within 0.1% up to a true strain of about 0.35. Almost all of the specimens were run to final fracture. 

S] Klar, E., Conrosion of Powder Metallurgy Materials, Metals Handbook, Ninth Edition, Vol. 13, Corrosion, ASM, Materials Park, OH, 1987, pp. 823-845. 

Rare earth effects on directionality 14 5.2. Powder metallurgy material 33... 

Nuclear Applications. Powder metallurgy is used in the fabrication of fuel elements as well as control, shielding, moderator, and other components of nuclear-power reactors (63) (see Nuclearreactors). The materials for fuel, moderator, and control parts of a reactor are thermodynamically unstable if heated to melting temperatures. These same materials are stable under P/M process conditions. It is possible, for example, to incorporate uranium or ceramic compounds in a metallic matrix, or to produce parts that are similar in the size and shape desired without effecting drastic changes in either the stmcture or surface conditions. OnlyHttle post-sintering treatment is necessary. 

R. M. German and R. G. lacocca, "Powder Metallurgy Processing and AppHcations for IntermetaUics," Mdvances in Powder Metallurgy (N Particulate Materials, Vol. 6, Metal Powder Industries federation, Princeton, N.J., 1993. 

F. H. Froes, "Synthesis of MetaUic Materials For Demanding Applications Using Powder Metallurgy Techniques," P/M in Merospace and Defense Technologies, Metal Powder Industries Federation, Princeton, N.J., 1991. 

It maybe economical, therefore, to use these materials at or near the cutting edge instead of as the whole insert. The development of tools of TiC (40—55%) or TiN (30—60%) in a steel matrix on a steel core using powder metallurgy technology suggests a similar approach for cemented carbides as the need arises. 

Powder Metallurgy, Vol. 7, Metals Handbook, 9th ed., ASM International, Materials Park, Ohio, 1984. 

The most chemical-resistant plastic commercially available today is tetrafluoroethylene or TFE (Teflon). This thermoplastic is practically unaffected by all alkahes and acids except fluorine and chlorine gas at elevated temperatures and molten metals. It retains its properties up to 260°C (500°F). Chlorotrifluoroethylene or CTFE (Kel-F, Plaskon) also possesses excellent corrosion resistance to almost all acids and alkalies up to 180°C (350°F). A Teflon derivative has been developed from the copolymerization of tetrafluoroethylene and hexafluoropropylene. This resin, FEP, has similar properties to TFE except that it is not recommended for continuous exposures at temperatures above 200°C (400°F). Also, FEP can be extruded on conventional extrusion equipment, while TFE parts must be made by comphcated powder-metallurgy techniques. Another version is poly-vinylidene fluoride, or PVF2 (Kynar), which has excellent resistance to alkahes and acids to 150°C (300°F). It can be extruded. A more recent development is a copolymer of CTFE and ethylene (Halar). This material has excellent resistance to strong inorganic acids, bases, and salts up to 150°C. It also can be extruded. 

VERBA-XRF eoneeption effieieney shows itself in numeral methods analyzing ferrous alloys and powder-like materials like raw materials for eement industry, slag, eleetrolysis preeipitations in non-ferrous metallurgy. 

Powder metallurgy is concerned with production and processing of powdery forms of metals and materials and of solid industrial products therefrom. 

Finally, it may be pointed out that none of the rare metals can be smelted directly from the ore. The concentrate must first be converted to a pure chemical compound which is utilized as the raw material for the production of the metal. The refractory rare metals are often obtained in the form of a powder or sponge. They are consolidated and refined by powder metallurgy techniques or by arc melting or by electron beam melting. In fact, the current refractory rare metals technology has been crucially dependent on the development of vacuum metallurgical techniques and processes. 

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