The effect of Nb morphology on the cyclic oxidation resistance of MoSi[sub 2]/20 vol pct Nb composites

Journal Article · Sun May 01 00:00:00 EDT 1994 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

OSTI ID:7174394

Alman, D E ^[1]; Stoloff, N S ^[2]

---

1. Bureau of Mines, Albany, OR (United States). Albany Research Center
2. Rensselaer Polytechnic Inst., Troy, NY (United States). Materials Engineering Dept.

The effect of Nb morphology on the 1,200 C cyclic oxidation resistance Of MoSi[sub 2]/20 vol pct Nb composites was investigated. Niobium was incorporated into MoSi[sub 2] as particles, random short fibers, and continuous aligned fibers. After oxidation, it was found that all the composites had lost weight and essentially disintegrated. This was attributed to spalling of both the Nb[sub 2]O[sub 5] scale and the MoSi[sub 2] matrix. The spalling of the matrix was a result of cracks originating in the oxidized Nb and propagating through the MoSi[sub 2] matrix. These cracks arose from two sources: (1) the volume expansion associated with the transformation of Nb to Nb[sub 2]O[sub 5] and (2) the difference in thermal expansion between Nb[sub 2]O[sub 5] and MoSi[sub 2]. However, it was found that the addition of smaller diameter Nb reinforcements tended to retard the disintegration of the composites. This was attributed to the effect of reinforcement size on CTE mismatch cracking.

• OSTI ID: 7174394
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 25:5; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360604* -- Materials-- Corrosion
Erosion
& Degradation
CHALCOGENIDES
CHEMICAL REACTIONS
COMPOSITE MATERIALS
CORROSION PRODUCTS
CORROSION RESISTANCE
DATA
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
MATERIALS
METALS
MOLYBDENUM COMPOUNDS
MOLYBDENUM SILICIDES
NIOBIUM
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
SILICIDES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS