Thermal stability of Sic-Scs-6 fiber-reinforced im1834 alloys
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Table I. Tensile Properties of the SiC-SCS-6 FiberReinforced IM1834 Alloys (vs = 0.35) after Different Thermal Treatment Conditions
Ultimate Tensile Strength (GPa) 2.30 and 2.13 2.28 2.03 2.30 2.38 and 2.17 1.30
Thermal Treatment As-processed 700 ~ h 700 ~ h 800 ~ h 800 ~ h 800 *C/2000 h
Thermal Stability of SiC-SCS-6 Fiber-Reinforced IMI834 Alloys
Elongation at Fracture (Pet) 1.27 and 1.23 1.20 1.04 1.24 1.23 and 1.23 0.73
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Young's Modulus (GPa) 210 and 195 208 207 214 210 and 190 210
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C-coating,700~
3 H.J. DUDEK, R. LEUCHT, and J. HEMPTENMACHER One of the major future applications of titanium matrix composites is as a material for airplane turbine components, e.g., in the compressor, t',2,31 Service temperatures of up to 800 ~ will be involved. This application objective will only be reached when it will be possible to solve two major material problems: first, a matrix with sufficient ductility at room temperature and sufficient strength at service temperatures has to be found; and second, the problem of fiber/matrix reaction at application temperatures has to be solved, t41 Presently, different matrix materials are under investigation, such as near a alloys, or2 alloys, and y-TiAl alloys.t,~] In composites with the high ductility IMI834 alloy (Ti5.8A1-4.0Sn-3.5Zr-0.7Nb-0.5Mo-0.35Si-0.06C in wt. pct) as matrix, the optimal tensile properties can be exploited: the ultimate tensile strength and Young's modulus values are in accordance with the prediction of the rule of mixtures, and an elongation at fracture of nearly 1.3 pet, typical of SiC fibers,t7.s] is measured. It was shown that in SiC-SCS-6 fiber-reinforced IMI834 composites, these properties are achieved up to temperatures of 1000 ~ The IMI834 alloy is one of the possible matrices for composites for turbine compressors. In the present study, results of the thermal stability of the SiC-SCS-6 fiber-reinforced IMI834 alloys are presented. The composites are processed by the fiber coating method. Fibers are coated with matrix alloy and are subsequently introduced into tubes also made of matrix material. These tubes are then consolidated by hot isostatic pressing ("hipping"), as described elsewhere.tT.S] In the present investigation, magnetron sputtering was used for fiber coating with the matrix alloy. The chemical composition of the coating corresponds to that of the target material and oxygen contamination in the coating can be minimized,t91 For the IMI834 alloy, a deficiency of Sn in the matrix coating was measured (3 wt pet instead of about
H.J. DUDEK, Head, and R. LEUCHT and J. HEMPTENMACHER, Members, are with the Metal Matrix Composite Group, German Aerospace Research Establishment (DLR), Institute for Materials Research, D-51140 Krln, Germany. Manuscript submitted October 3, 1995. METALLURGICAL AND MATERIALS TRANSACTIONS A
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