Influence of fabrication technique on the fiber pushout behavior in a sapphire-reinforced NiAl matrix composite

Journal Article · Sun Jan 01 00:00:00 EST 1995 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02669807· OSTI ID:6607308

Asthana, R; Bowman, R R ^[1]; Tewari, S N ^[2]

---

1. NASA Lewis Research Center, Cleveland, OH (United States). Materials Division
2. Cleveland State Univ., OH (United States)

Directional solidification (DS) of powder-cloth'' (PC) processed sapphire-NiAl composites was carried out to examined the influence of fabrication technique on the fiber-matrix interfacial shear strength, measured using a fiber-pushout technique. The DS process replaced the fine, equiaxed NiAl grain structure of the PC composites with an oriented grain structure comprised of large columnar NiAl grains aligned parallel to the fiber axis, with fibers either completely engulfed within the NiAl grains or anchored at one to three grain boundaries. The load-displacement behavior during the pushout test exhibited an initial pseudoelastic'' response, followed by an inelastic'' response, and finally a frictional'' sliding response. The fiber-matrix interfacial shear strength and the fracture behavior during fiber pushout were investigated using an interrupted pushout test and fractography, as functions of specimen thickness and fabrication technique. The composites fabricated using the PC and the DS techniques had different matrix and interface structures and appreciably different interfacial shear strengths. In the DS composites, where the fiber-matrix interfaces were identical for all the fibers, the interfacial debond shear stresses were larger for the fibers embedded completely within the NiAl grains and smaller for the fibers anchored at a few grain boundaries. The matrix grain boundaries coincident on sapphire fibers were observed to be the preferred sties for crack formation and propagation.

• OSTI ID: 6607308
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Vol. 26:1; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
FABRICATION
MECHANICAL PROPERTIES
ALUMINIUM OXIDES
COMPOSITE MATERIALS
INTERFACES
NICKEL ALLOYS
FAILURES
FRACTURE PROPERTIES
MICROSTRUCTURE
SHEAR PROPERTIES
ALLOYS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
MATERIALS
OXIDES
OXYGEN COMPOUNDS
360603* - Materials- Properties
360601 - Other Materials- Preparation & Manufacture