In situ transmission electron microscopy study of ordering in a splat-cooled Ni-20 at.% Mo alloy

Journal Article · Wed Mar 01 04:00:00 EST 1995 · Materials Characterization

DOI:https://doi.org/10.1016/1044-5803(94)00053-N· OSTI ID:51682

Cao, S; Brooks, C R ^[1]; Allard, L ^[2]

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1. Univ. of Tennessee, Knoxville, TN (United States)
2. Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

Using transmission electron microscopy, the microstructure of splat-cooled (through hammer and anvil) Ni-20 at.% Mo specimens has been examined for the as-cooled condition and for heated samples. In the as-cooled condition, the structure consisted of columnar grains with a cell structure of about 0.2 {mu}m. The cooling rate was estimated to be about 10{sup 6} K/s; but even for this rapid cooling, weak short-range order (SRO) was present. Specimens were step-heated in situ in the transmission electron microscope to a specific temperature, held for 5 minutes, cooled to 25 C for observation, then reheated to a higher temperature, and the process repeated for increasingly higher temperatures. At 500 C, the intensity of the SRO diffraction spots increased. At 665 C, these SRO spots split into the long-range order (LRO) positions. At 765 C, LRO was established with a fine (about 0.05{mu}m) domain structure. As the heating temperature increased, the cell structure became weak and disappeared at about 765 C.

• OSTI ID: 51682
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Journal Issue: 2 Vol. 34; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL STRUCTURE
HEAT TREATMENTS
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL BASE ALLOYS
ORDER-DISORDER TRANSFORMATIONS
PHASE TRANSFORMATIONS
SPLAT COOLING