Measurement of transformation kinetics in Ni-B metastable crystalline and amorphous alloys by DSC

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6419815

Roth, E P; Campbell, A N; Mullendore, A W

Chemical vapor deposition (CVD) has been used to prepare amorphous and polycrystalline films of Ni-B from nickel carbonyl and diborane at 155/sup 0/C. Three low-boron content samples containing 2.6, 5.3, and 13.0 at. % boron were prepared which had a fine-grained polycrystalline structure of fcc nickel supersaturated with boron. A high-boron content sample was prepared containing 37 at. % boron and was completely amorphous. Upon heating above 300/sup 0/C, Ni/sub 3/B precipitates from the polycrystalline low-boron content samples, while Ni/sub 2/B and Ni/sub 4/B/sub 3/ forms from the high-boron content sample near 500/sup 0/C. While the mechanical properties of some of these alloys are enhanced during the initial stages of transformation, the coarsening of the microstructure during extensive annealing is accompanied by a decrease in strength and hardness. A DSC study of the Ni-B alloys was undertaken to assess the thermal stability of the as-deposited microstructure. The enthalpies and kinetics of intermetallic formation were studied with both constant-heating-rate (CHR) and isothermal measurement techniques.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6419815
• Report Number(s): SAND-87-0591C; CONF-870988-1; ON: DE87010953
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ACTIVATION ENERGY
ALLOYS
AMORPHOUS STATE
BORIDES
BORON ALLOYS
BORON COMPOUNDS
CALORIMETRY
ENERGY
ENTHALPY
FORMATION HEAT
INTERMETALLIC COMPOUNDS
KINETICS
METALLIC GLASSES
NICKEL ALLOYS
NICKEL BORIDES
NICKEL COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
REACTION HEAT
SPECIFIC HEAT
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS