Microstructures and tensile properties of some γ-TiAl alloys made from elemental powders
About: This article is published in Scripta Metallurgica Et Materialia.The article was published on 1992-12-01. It has received 5 citations till now. The article focuses on the topics: Ultimate tensile strength.
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TL;DR: In this article, a self-propagating, high-temperature synthesis reaction (SHS) was initiated at the interface between dissimilar elemental metal foils, resulting in a fully dense, well-bonded metal-intermetallic layered composite.
Abstract: A processing technique for the fabrication of layered metal-intermetallic composites is presented, in which a self-propagating, high-temperature synthesis reaction (SHS) was initiated at the interface between dissimilar elemental metal foils. The resultant composite microstructure consisted of a fully dense, well-bonded metal-intermetallic layered composite. In this United States Bureau of Mines study, metal (Fe, Ni, or Ti) foils were reacted with Al foils to produce metal-metal aluminide layered composites. Tensile tests conducted at room temperature revealed that composites could be designed to behave in a high-strength and high-toughness manner by altering the thicknesses of the starting elemental foils. Failure characteristics revealed that the processes that govern ductilevs brittle behavior of the composites occur early in the fracture.
61 citations
54 citations
TL;DR: This article showed that reactive hot isostatic pressing (RHIPing) based on the self-propagating exothermic reaction of the constituent powders allows homogeneous, high-density material to be made Controlled process parameters include green density, prior degassing, the powder size distribution, heating rate, pressure, and homogenizing schedule.
Abstract: The unusual combination of high-temperature strength and room-temperature ductility makes compounds based on RuAl attractive for structural applications Difficulties inherent in the manufacture of RuAl by melt processing can be circumvented by powder metallurgical (PM) techniques The present work shows that reactive hot isostatic pressing (RHIPing) based on the self-propagating exothermic reaction of the constituent powders allows homogeneous, high-density material to be made Controlled process parameters include green density, prior degassing, the powder size distribution, heating rate, pressure, and homogenizing schedule The nature of the reaction products was found to be determined primarily by the applied pressure during combustion While concurrent pressure is required to ensure densification, pressurization leads to the formation of a host of nonequilibrium phases that necessitate extended homogenizing practices to drive the reaction to completion The readily assimilable process parameters allow the production of structural components based on RuAl to be envisaged
27 citations
TL;DR: In this article, the results of three major German national materials research projects: (i) gas turbine components, (ii) sheet and foil material, and (iii) automotive components.
Abstract: Research and applications of γ-base titanium aluminide alloys in Germany and Austria are reviewed. Special emphasis is given to the results of three major German national materials research projects: (i) gas turbine components, (ii) sheet and foil material, and (iii) automotive components. TiAl turbine blades and valves were successfully tested, and sheets are planned to be used in hypersonic applications. Powder metallurgy methods have been developed as alternative processing routes. Basic investigations on phase diagrams were carried out as a base for alloy development and high-resolution electron microscopic methods have led to a better understanding of the mechanical behaviour.
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TL;DR: In this article, the authors present a review of the current understanding of the above specific aspects and the processing-microstructure-property relationships, and identify pacing problems and applications, as well as identify pacing issues and applications.
Abstract: During the last two years remarkable improvements have been made in the properties (such as toughness and creep) and processing technology of gamma titanium aluminides, making them potentially viable engineering alloys for high-temperature structural applications. These achievements were made possible by a greater understanding of both the fundamental and the practical aspects of these aluminides, such as phase relationships, the effects of alloying elements, deformation mechanisms, microstructure evolution and processing. This article reviews the current understanding of the above specific aspects and the processing-microstructure-property relationships, and identifies pacing problems and applications.
571 citations
TL;DR: In this paper, a great deal of effort has been made to improve these ductile properties through chemistry modification and microstructure control, and some success has met with some success.
Abstract: Titanium-aluminide alloys based on TiAl have an excellent potential to become one of the most important aerospace materials because of their low density, high melting temperature, good elevated-temperature strength and modulus retention, high resistance to oxidation and hydrogen absorption, and excellent creep properties. The chief roadblock to their application is poor ductility at low to intermediate temperatures that results in low fracture toughness and a fast fatigue-crack growth rate. During the last several years, a great deal of effort has been made to improve these ductile properties. These endeavors have met with some success through chemistry modification and microstructure control.
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