Criticism Of the paper titled ‘Solidification thermal parameters, microstructural evolution and dendritic growth in an AlCuNi alloy’ by Correa et al.

2021 ◽  
pp. 1-5
Author(s):  
Murat Tiryakioğlu ◽  
Güven Kurtuldu
Keyword(s):  
Microstructural Evolution ◽  
Dendritic Growth ◽  
Thermal Parameters

Solidification thermal parameters, microstructural evolution and dendritic growth in an AlCuNi alloy

2020 ◽  
pp. 1-9
Author(s):  
Edinaldo G. Correa ◽  
Evandro S. Militão ◽  
Luiz G. Nascimento ◽  
Ivaldo L. Ferreira ◽  
Otávio L. Rocha
Keyword(s):  
Microstructural Evolution ◽  
Dendritic Growth ◽  
Thermal Parameters

scholarly journals Solidification thermal parameters and dendritic growth during the horizontal directional solidification of Al-7wt.%Si alloy

2014 ◽  
Vol 67 (3) ◽  
pp. 265-270 ◽  
Author(s):  
Diego de Leon Brito Carvalho ◽  
Thiago Antônio Paixão de Sousa Costa ◽  
Antonio Luciano Seabra Moreira ◽  
Maria Adrina Paixão de Souza da Silva ◽  
José Marcelino Dias Filho ◽  
...  
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Comparative Study ◽  
Directional Solidification ◽  
Power Law ◽  
Dendritic Growth ◽  
Primary Dendrite ◽  
Thermal Parameters ◽  
Hypoeutectic Alloy ◽  
Power Law Function

The main purpose of this work is to investigate the influence of thermal parameters such as growth rate (V L) and cooling rate (T R) on the primary dendrite arm spacings (λ1) during the horizontal transient directional solidification of Al-7wt.%Si hypoeutectic alloy. The primary dendrite spacings were measured along the length of the samples and correlated with these thermal parameters. The variation of dendrite spacings is expressed as a power law function of V L and T R given by the formulas λ1 = 55(V L)-1.1 and λ1 = 212 (T R)-0.55, respectively. A comparative study between the results of this work and those from the literature proposed to investigate these dendrite spacings during the upward and downward vertical directional solidification of Al-7wt.%Si alloy is also conducted. Finally, the experimental data are compared with some predictive dendritic models from the literature.

Microstructural Evolution in Reduced TiO2

1981 ◽  
Vol 39 ◽  
pp. 74-75
Author(s):  
W. T. Donlon ◽  
S. Shinozaki ◽  
E. M. Logothetis ◽  
W. Kaizer
Keyword(s):  
Microstructural Evolution ◽  
Point Defects ◽  
Extended Defects ◽  
Small Deviations ◽  
Controlled Atmospheres ◽  
Limited Solubility ◽  
Thin Foils ◽  
Heat Treated ◽  
Porous Polycrystalline ◽  
Crystallographic Shear

Since point defects have a limited solubility in the rutile (TiO2) lattice, small deviations from stoichiometry are known to produce crystallographic shear (CS) planes which accomodate local variations in composition. The material used in this study was porous polycrystalline TiO2 (60% dense), in the form of 3mm. diameter disks, 1mm thick. Samples were mechanically polished, ion-milled by conventional techniques, and initially examined with the use of a Siemens EM102. The electron transparent thin foils were then heat-treated under controlled atmospheres of CO/CO2 and H2 and reexamined in the same manner.The “as-received” material contained mostly TiO2 grains (∼5μm diameter) which had no extended defects. Several grains however, aid exhibit a structure similar to micro-twinned grains observed in reduced rutile. Lattice fringe images (Fig. 1) of these grains reveal that the adjoining layers are not simply twin related variants of a single TinO2n-1 compound. Rather these layers (100 - 250 Å wide) are alternately comprised of stoichiometric TiO2 (rutile) and reduced TiO2 in the form of Ti8O15, with the Ti8O15 layers on either side of the TiO2 being twin related.

Convective effects in microgravity on dendritic growth kinetics and morphologies

1996 ◽  
Author(s):  
M. Glicksman ◽  
M. Koss ◽  
L. Bushnell ◽  
J. LaCombe ◽  
E. Winsa
Keyword(s):  
Growth Kinetics ◽  
Dendritic Growth

Dendritic Growth Failure of a Mesa Diode

1997 ◽  
Author(s):  
P. Singh ◽  
V. Cozzolino ◽  
G. Galyon ◽  
R. Logan ◽  
K. Troccia ◽  
...  
Keyword(s):  
Electric Fields ◽  
Dendritic Growth ◽  
Silicon Oxide ◽  
Impact Ionization ◽  
Electron Tunneling ◽  
Growth Failure ◽  
Side Wall ◽  
Oxide Interface ◽  
Band Bending ◽  
Cross Section Area

Abstract The time delayed failure of a mesa diode is explained on the basis of dendritic growth on the oxide passivated diode side walls. Lead dendrites nucleated at the p+ side Pb-Sn solder metallization and grew towards the n side metallization. The infinitesimal cross section area of the dendrites was not sufficient to allow them to directly affect the electrical behavior of the high voltage power diodes. However, the electric fields associated with the dendrites caused sharp band bending near the silicon-oxide interface leading to electron tunneling across the band gap at velocities high enough to cause impact ionization and ultimately the avalanche breakdown of the diode. Damage was confined to a narrow path on the diode side wall because of the limited influence of the electric field associated with the dendrite. The paper presents experimental details that led to the discovery of the dendrites. The observed failures are explained in the context of classical semiconductor physics and electrochemistry.

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