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Title: Microlaminated high temperature intermetallic composites

Journal Article · · Scripta Metallurgica et Materialia; (United States)
; ;  [1]; ; ;  [2]
  1. GE Corporate Research and Development, Schenectady, NY (United States)
  2. Univ. of California, Santa Barbara, CA (United States). Materials Dept.

The thrust to weight ratio of aircraft engines is limited by the density and elevated temperature capability of high temperature turbine materials. Single crystal superalloys, which are the current state-of-the-art in high temperature turbine blade materials, have limited potential for further increases in temperature capability. High temperature intermetallics offer the advantage of higher specific strength and higher temperature capability, but lack ductility and fracture toughness below 1,000 C. By compositing these very high temperature intermetallics with ductile metals, toughening may be improved to the point where the composites have applicability in aircraft engine turbine sections. Lamination of ductile metals with continuous intermetallic layers offers one means of producing such composites. Small lamellae thicknesses may have advantages related to intrinsic defect sizes and the effectiveness of ductile reinforcements in load-controlled applications where strength is important. Intermetallic composites will require a refractory metal for toughening because of the need for metal strength at temperatures above 1,100 C. Niobium-base alloys were selected as the toughening layer in this study because of experience with oxidation-resistant niobium alloys with low densities compared to superalloys and the existence of metal-intermetallic systems in equilibrium at high temperatures. Two microlaminated composite systems, Nb[sub 3]Al-Nb and Cr[sub 2]Nb(Cr) were chosen for microstructural and mechanical property evaluation. The choice of systems was partially based upon knowledge of phase relations between the metal and the intermetallic compositions.

OSTI ID:
6987814
Journal Information:
Scripta Metallurgica et Materialia; (United States), Vol. 31:11; ISSN 0956-716X
Country of Publication:
United States
Language:
English