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81.
Andreas Mortensen Ph.D. Veronique J. Michaud Ph.D. Merton C. Flemings Sc.D. 《JOM Journal of the Minerals, Metals and Materials Society》1993,45(1):36-43
Pressure infiltration of liquid metal is one of the most important processing routes for the production of aluminum-matrix composites having a self-supporting reinforcement phase. This article briefly examines the physical phenomena governing infiltration processes, to present practical guidelines derived from their analysis for optimization of the process and the materials produced. Engineering aspects that are pertinent to infiltration techniques, including preform preparation, process configurations, flow control, and innovative processes, are summarized. 相似文献
82.
Robert E. Green Jr. Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1992,44(10):12-16
Although nondestructive techniques have been used almost exclusively to detect macroscopic defects in structures or devices, it has become increasingly evident that it is both practical and cost-effective to expand the role of nondestructive evaluation to include all aspects of materials production. In recent years, classical nondestructive testing techniques have been augmented by more sophisticated methods for characterizing the microstructure and the associated physical and chemical properties of materials. 相似文献
83.
J. J. Stephens Ph.D. P. T. Vianco Ph.D. F. M. Hosking M.S. 《JOM Journal of the Minerals, Metals and Materials Society》1996,48(1):54-58
The active metal brazing of ceramics holds the opportunity to design metal-ceramic brazing processes without conventional metallization and nickel-plating steps. Because of their intermediate thermal coefficient of expansion (TCE) properties, molybdenum and the TZM-Mo alloy (Mo-0.5Ti-0.08Zr) are attractive candidates for joining to silicon- nitride ceramics. The recently developed Fe-Ni-Co-based Thermo-Span? alloy, with reduced TCE from room temperature up to ≈400°C, is also an attractive candidate material for 700°C joint service applications. This article discusses the wetting, solid-state aging, and mechanical behavior of unalloyed molybdenum, TZM-Moalloy, Thermo-Span alloy, and silicon-nitride ceramic brazes made with three different active-metal braze alloys. 相似文献
84.
Paul T. Vianco Ph.D. Darrel R. Frear Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1993,45(7):14-19
The use of soft solders, particularly those containing lead, dates back nearly 5,000 years. Solders similar to the materials used to seal the aqueducts of ancient Rome are now an important building block in the manufacture of high-speed computer assemblies. This history attests to the technological versatility of soft solders and, in particular, the solder alloys that contain lead. However, the health effects of prolonged exposure to lead have also been documented; measures to limit human exposure—at the work place and indirectly through the environment—are being considered. The successful introduction of lead-free solders into future electronic products will rely heavily upon their solderability, which can be evaluated by test procedures such as the meniscometer/wetting balance technique and the capillary flow test. 相似文献
85.
B. R. Patterson Ph.D. C. S. Aria M.S. 《JOM Journal of the Minerals, Metals and Materials Society》1989,41(8):22-25
For metal and ceramic injection molding procedures which use wax binders in the production of powder-based parts, melt wicking is commonly employed to debind the components prior to sintering. Because debinding is often a time-consuming procedure, the influence of such process variables as powder size, part height, green density and temperature have been investigated to reduce the amount of time required for debinding by melt wicking. 相似文献
86.
A. R. Boccaccini Ph.D. C. B. Ponton Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1995,47(10):34-37
A novel, cost-effective processing technique for manufacturing ceramic-matrix composites (CMCs) containing two-dimensional woven-fiber reinforcement has been developed. The technique relies on the electrophoretic deposition (EPD) of ceramic sols on/into the fiber preforms to achieve the required impregnation. The laboratory-scale results achieved thus far indicate that the processing approach offers great potential for the manufacture of high-quality, composite products with dual-component oxide matrices for high-temperature structural applications. 相似文献
87.
Clark A. Updike M.S. Ram B. Bhagat Ph.D. Martin J. Pechersky Ph.D. Maurice F. Amateau Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1990,42(3):42-46
Metal-matrix composites may offer better damping properties than unreinforced alloys. Because damping properties (and metal-matrix composites) are becoming important in airframe design, the damping capabilities of a number of aluminum-matrix composites were measured over a wide range of frequencies at low strain amplitudes, using a new laser vibrometer technique. Silicon carbide and alumina reinforcements resulted in a material with damping properties similar to that of unreinforced aluminum 6061-T6, but unidirectional and planar-random graphite continuous-fiber reinforcements increased the damping by 5 and 14 times, respectively. The increased damping of the continuous fiber composites is attributed to the absence of interfacial reaction resulting from the high-pressure infiltration method used for their manufacture. 相似文献
88.
Dr. R. B. Schwarz Ph.D. Dr. P. Nash Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1989,41(1):27-31
The recent discovery that amorphous alloy powders can be prepared by mechanically alloying a mixture of pure crystalline intermetallics is opening new windows to the synthesis of engineering materials. Amorphous powders synthesized by mechanical alloying may find application in the design of structural alloys, high thermal conductivity alloys, and metal-matrix composites. 相似文献
89.
T. E. Howson D.E.Sc. H. E. Delgado Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1989,41(2):32-34
By simulating the flow of metal in forging, engineers can eliminate defects and undesirable flow patterns. Localized deformation heating of the forging can be predicted and avoided, with a resulting improvement of quality. 相似文献
90.
C. T. Liu Ph.D. K. S. Kumar Ph.D. 《JOM Journal of the Minerals, Metals and Materials Society》1993,45(5):38-44
This article summarizes recent progress in research and development on nickel and iron aluminide intermetallic alloys. Ordered intermetallics possess attractive properties for structural applications at elevated temperatures in hostile environments; however, brittle failure and poor fracture resistance limit their use as engineering materials. In recent years, efforts to understand this brittle fracture behavior have identified both intrinsic and extrinsic factors governing brittle fracture. Parallel work on alloy design using physical metallurgy principles has led to the development of aluminide alloys with improved mechanical and metallurgical properties for structural use. 相似文献