Transmission electron microscopy study of phase transformations in ternary Ni/sub 4/Mo-based alloys containing 0 to 4 weight percent chromium

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6923903

Vasudevan, K

Phase transformations in the binary Ni/sub 4/Mo alloy and ternary Ni/sub 4/Mo alloys containing 0 to 4 wt% chromium are reported using electric resistivity and microhardness measurements, optical scanning, and transmission electron microscopy (TEM). The transformation behavior was studied by resistivity measurements during continuous heating, cooling, or isothermally. The isothermal transformation behavior was also investigated in alloys aged at 600, 700, 800, and 850/sup 0/C for times to 4500 hours. The resistivity changes associated with short range order (SRO) and long-range order (LRO) in Ni/sub 4/Mo have been completely characterized. The negative temperature coefficient of resistivity that is observed in the SRO state, and the change in slope of the LRO resistivity-temperature curve are explained on the basis of s-d electron scattering. The )111) and )110) fcc striations observed in the optical microstructure of ordered Ni/sub 4/MO were studied using TEM and explained on the basis of structural considerations. The isothermal transformation behavior of ternary Ni/sub 4/Mo alloys containing chromium in the range 2 to 4 wt% aged at 850, 800, 700, and 600/sup 0/C was studied. A variety of Mo-rich second phases, such as DO/sub 22/, Ni/sub 3/Mo, Ni/sub 2/MO, and eta-carbides is observed.

• Research Organization: Tennessee Univ., Knoxville (USA)
• OSTI ID: 6923903
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOY SYSTEMS
ALLOYS
BINARY ALLOY SYSTEMS
CHROMIUM ALLOYS
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
HARDNESS
HIGH TEMPERATURE
MECHANICAL PROPERTIES
MICROHARDNESS
MICROSCOPY
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL ALLOYS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
TERNARY ALLOY SYSTEMS
TRANSMISSION ELECTRON MICROSCOPY
VERY HIGH TEMPERATURE