Effects of a Free Surface on the Kinetics of Annealing Processes

Metal Science ◽  
1975 ◽  
Vol 9 (1) ◽  
pp. 22-26 ◽  
Author(s):  
P.-A. Comte ◽  
W. Form
Keyword(s):  
2020 ◽  
Vol 56 (8) ◽  
pp. 5173-5189
Author(s):  
Y. Fu ◽  
C. Kwakernaak ◽  
J. C. Brouwer ◽  
W. G. Sloof ◽  
E. Brück ◽  
...  

Abstract The precipitation of supersaturated solutes at free surfaces in ternary Fe–3Au–4W and binary Fe–3Au and Fe–4W alloys (composition in weight percentage) for different ageing times was investigated at a temperature of 700 °C. The time evolution of the surface precipitation is compared among the three alloys to investigate the interplay between the Au and W solutes in the ternary system. The Au-rich grain-interior surface precipitates show a similar size and kinetics in the Fe–Au–W and Fe–Au alloys, while the W-rich grain-interior surface precipitates show a smaller size and a higher number density in the Fe–Au–W alloy compared to the Fe–W alloy. The kinetics of the precipitation on the external free surface for the ternary Fe–Au–W alloy is compared to the previously studied precipitation on the internal surfaces of the grain-boundary cavities during creep loading of the same alloy. Graphical abstract


2021 ◽  
Vol 57 (02) ◽  
pp. 75-93
Author(s):  
P. Hora ◽  
A. Machová ◽  
J. Červ ◽  
A. Uhnáková

1990 ◽  
Vol 5 (2) ◽  
pp. 378-384 ◽  
Author(s):  
T. C. Chou

Oxidation of IrAl alloys (50-50 at.%) was conducted at 1300 and 1600°C in air for different times. Due to the outward diffusion of Al atoms and subsequent oxidation, the formation of Al2O3 is accompanied with the generation of an Ir-rich phase in the vicinity areas. The oxidation zone is separated from the bulk IrAl alloy by a phase boundary. In the oxidation zones, alternating layers of Al2O3 and Ir-rich phase are produced at 1300°C, while irregularly intertwined; Al2O3 and Ir-rich phase are produced at 1600 °C. The discontinuous formation of Al2O3 gives rise to internal oxidation of the IrAl alloys. The thickness of the Al2O3 layer is in the range of tens of micrometer, and it grows thicker as its location gets farther away from the free surface. The formation of an Al2O3/Ir-rich phase layered structure is discussed based on the diffusion kinetics of O, Al, and Ir, the chemical reactivities of Al and Ir with respect to O, and the nucleation and growth kinetics of Al2O3.


2004 ◽  
Vol 69 (2) ◽  
pp. 292-308 ◽  
Author(s):  
Francesco Tadini Buoninsegni ◽  
Andrea Dolfi ◽  
Rolando Guidelli

The homogeneous, defect-free surface of a hanging mercury drop electrode was used to self-assemble films apt for the investigation of two photobioelectrochemical systems. Monolayers of straight-chain C12-C18 alkane-1-thiols were anchored to a hanging mercury drop electrode and a film of chlorophyll was self-assembled on the top of them. The dependence of the photocurrents generated by illumination of the chlorophyll film with red light, on the thickness of the alkane-1-thiol monolayer and the applied potential is discussed. The photocurrents of purple membrane fragments, adsorbed on a mixed hexadecane-1-thiol/ dioleoylphosphatidylcholine bilayer self-assembled on mercury, were investigated in the presence of sodium perchlorate, chloride and acetate. The effect of the anions on the kinetics of the light-driven proton transport by bacteriorhodopsin has been determined.


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