Activation parameters of high-temperature creep in polycrystalline nickel at ambient and high pressures

Journal Article · Wed Jan 01 04:00:00 EST 1992 · Acta Metallurgica; (United States)

DOI:https://doi.org/10.1016/0956-7151(92)90209-W· OSTI ID:7111434

Meagher, S; Groza, J; Mukherjee, A K ^[1]; Borch, R S; Green, II, H W ^[2]

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1. Dept. of Mechanical, Aeronautical and Materials Engineering, Univ. of California, Davis, CA (US)
2. Dept. of Geology, Univ. of California, Davis, CA (US)

This paper reports on polycrystalline specimens of pure nickel deformed in uniaxial compression at temperatures of 1000-1550 K, strain rates of 1 {times} 10{sup {minus}5} {minus}3 {times} 10{sup {minus}3} s{sup {minus}1} and pressures of 0.1-1500 MPa, in order to determine the activation parameters of high temperature creep. Experiments at 0.1 MPa were conducted in an MTS apparatus with the specimen immersed in a molten heat-treating salt to prevent oxidation. The data show a decreasing power-law stress exponent with decreasing normalized steady-state flow stress ({sigma}/G), approaching the natural law value of n = 3 at normalized stresses {lt}10{sup {minus}4}. In contrast, the activation energy is constant over our range of temperatures (T/T{sub m} = 0.55-0.90), and is indistinguishable from the activation energy of self-diffusion (284 kJ/mol). High pressure experiments were indistinguishable from the activation energy of self-diffusion (284 kJ/mol). High pressure experiments were conducted in a modified piston-cylinder apparatus using the same molten heat-treating salt for the confining medium. The small activation volume could not be resolved; however, the trend of the high pressure data parallels that of the 0.1 MPa data with a systematic offset, and is consistent with the measured activation volume of self diffusion. Specimens deformed at 0.1 MPa exhibited significant strain-enhanced grain growth; this effect is greatly reduced under hydrostatic pressure, whereas subgrain size was less affected.

• OSTI ID: 7111434
• Journal Information: Acta Metallurgica; (United States), Journal Name: Acta Metallurgica; (United States) Vol. 40:1; ISSN 0001-6160; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
360104 -- Metals & Alloys-- Physical Properties
360105 -- Metals & Alloys-- Corrosion & Erosion
ACTIVATION ENERGY
CHEMICAL REACTIONS
CORROSION
CORROSION INHIBITORS
CREEP
CRYSTALS
DATA
DEFORMATION
ELEMENTS
ENERGY
EXPERIMENTAL DATA
FLOW STRESS
HIGH PRESSURE
INFORMATION
MECHANICAL PROPERTIES
METALS
NICKEL
NUMERICAL DATA
PHYSICAL PROPERTIES
POLYCRYSTALS
STEADY-STATE CONDITIONS
STRESS CORROSION
STRESSES
TEMPERATURE EFFECTS
TEMPERATURE RANGE
TEMPERATURE RANGE 1000-4000 K
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS