Disordering phase transformation in (Ni/sub 70/Fe/sub 30/)/sub 3/(V/sub 98-x/Al/sub x/Ti/sub 2/) alloys with 0 less than or equal to x less than or equal to 80

Conference · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5987827

DasGupta, A; Horton, J A

The sequence of disordering transformation processes in the A/sub 3/B type alloy series (Ni/sub 70/Fe/sub 30/)/sub 3/(V/sub 98-x/Al/sub x/Ti/sub 2/), currently under development for high-temperature structural applications, was studied by differential scanning calorimetry (DSC), x-ray diffraction, optical microscopy, and transmission electron microscopy (TEM). Results of DSC show that in all alloys there are two endothermic stages of phase transformation from the ordered to the disordered state. With increasing x, the disordering transition temperature, T/sub c/, reaches a maximum approx.1000/sup 0/C at x approx. = 50, and then decreases. Interrupted heating, followed by water quenching, was used to characterize the crystal structure and the microstructure of the intermediate phases. For the x = 20 alloy, TEM observations showed ordered regions of DO/sub 22/ phase in a matrix of disordered fcc(Al) phase at intermediate temperatures. The ordered domains transformed morphologically into cuboid like regions at higher temperatures. From a combined study by all the techniques, in alloys with x between 0 and 20, the sequence of phase transformations upon heating is: DO/sub 22/ ..-->.. DO/sub 22/ + Al ..-->.. Al, whereas in alloys with greater than or equal to 40, the major sequence is /sub 2/ + B2 ..-->.. L1/sub 2/ + Al ..-->.. Al.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5987827
• Report Number(s): CONF-841157-102; ON: DE86002186
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ALUMINIUM ALLOYS
CALORIMETRY
COHERENT SCATTERING
DIFFRACTION
ELECTRON MICROSCOPY
INTERMETALLIC COMPOUNDS
IRON ALLOYS
MICROSCOPY
NICKEL ALLOYS
ORDER-DISORDER TRANSFORMATIONS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SCATTERING
THERMODYNAMIC PROPERTIES
TITANIUM ALLOYS
TRANSITION TEMPERATURE
VANADIUM ALLOYS
X-RAY DIFFRACTION