Interfacial chemical stability during diffusion bonding of Al{sub 2}O{sub 3}-fibers with Ni{sub 3}Al- and NiAl-matrices
- RWTH Aachen (Germany). Inst. fuer Metallkunde und Metallphysik
Intermetallic matrix composites of Ni{sub 3}Al- and NiAl-matrix reinforced with continuous Al{sub 2}O{sub 3} fibers were investigated by means of TEM, EDS and HRTEM with regard to interfacial reactions during diffusion bonding. The specimens were fabricated by hot pressing both in vacuum (2 {times} 10{sup {minus}4} Pa) and in air for 2--8 h at 1,200--1,280 C for the Ni{sub 3}Al-matrix and at 1,300--1,450 C for the NiAl-matrix, respectively. Experimental results revealed a diffusion of Ni from the Ni{sub 3}Al-matrix into the fibers during diffusion bonding. As a consequence of the diffusion process a chemical reaction took place in the specimens with Ni{sub 3}Al-matrix hot pressed in air; particle-shaped reaction products (Ni-spinel) were observed in the fibers. In addition, thin films of about 5--20 mm thickness appeared in some sections of the interface in specimens with Ni{sub 3}Al-matrix hot pressed in vacuum. In the film the lattice planes were disordered and porous. In other sections (Mg, Ni)-spinels (Mg,Ni)Al{sub 2}O{sub 4} were formed as interfacial reaction products, when MgO as impurity had segregated to the surface of the fibers prior to diffusion bonding. In contrast to the results on Ni{sub 3}Al, specimens with NiAl-Matrix showed excellent chemical stability during hot pressing both in vacuum and in air; only minor diffusion of Ni into the fibers and no reaction products could be detected. The potential influence of interfacial behavior on the mechanical properties of the composites will be discussed.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 271780
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 6 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
- Country of Publication:
- United States
- Language:
- English
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