The role of chemical free energy and elastic strain in the nucleation of zirconium hydride

2013 ◽  
Vol 441 (1-3) ◽  
pp. 395-401 ◽  
Author(s):  
A.T.W. Barrow ◽  
C. Toffolon-Masclet ◽  
J. Almer ◽  
M.R. Daymond
Keyword(s):  
Free Energy ◽  
Elastic Strain ◽  
Zirconium Hydride ◽  
Chemical Free Energy

Estimation of the System Free Energy of the Lath Martensite Phase in High Cr Ferritic Steels

2006 ◽  
Vol 15-17 ◽  
pp. 690-695 ◽  
Author(s):  
Tomonori Kunieda ◽  
Kensuke Akada ◽  
Yoshinori Murata ◽  
Toshiyuki Koyama ◽  
Masahiko Morinaga
Keyword(s):  
Free Energy ◽  
Ternary Alloy ◽  
Elastic Strain ◽  
Lath Martensite ◽  
Elastic Strain Energy ◽  
Martensite Phase ◽  
Interfacial Energies ◽  
Martensite Packet ◽  
Chemical Free Energy ◽  
Martensite Microstructure

The system free energy was estimated for the martensite phase of an Fe-Cr-C ternary alloy, 12Cr2W and 12Cr2W0.5Re steels. The system free energy of the martensite phase is defined as, Gsys = G0 + Estr + Esurf , where G0 is the chemical free energy, Esurf is the interfacial energy for the boundaries in the martensite microstructure, and Estr is the elastic strain energy due to the dislocations in the martensite phase. From the experimental results on SEM/EBSD, the total interfacial energies were estimated to be 0.83J/mol for the ternary alloy and 4.8J/mol for both 12Cr2W and 12Cr2W0.5Re steels in the as-quenched state. Also, the elastic strain energies were estimated to be 7.1J/mol for the ternary alloy, 9.6J/mol for 12Cr2W steel and 9.8J/mol for 12Cr2W0.5Re steel in the as-quenched state. So, the system free energy was about 7.9J/mol for ternary alloy. On the other hand, the system free energy was about 14.4J/mol for 12Cr2W steel and 14.6J/mol for 12Cr2W0.5Re steel. So, these microstructural energies operate as a driving force for the microstructure evolution, e.g., recovery of dislocations and the coarsening of the sub-structures such as martensite-packet, -block and -lath.

Stress Dependence of Microstructural Evolution in Heat Resistant Steels

2010 ◽  
Vol 654-656 ◽  
pp. 190-193
Author(s):  
Yoshinori Murata ◽  
Yoshihiro Saoto ◽  
Yuhki Tsukada ◽  
Toshiyuki Koyama ◽  
Masahiko Morinaga ◽  
...  
Keyword(s):  
Free Energy ◽  
Relaxation Time ◽  
Surface Energy ◽  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Stress Dependence ◽  
Heat Resistant ◽  
Chemical Free Energy ◽  
Heat Resistant Steels

The state of the microstructure of ferritic heat resistant steels during creep was evaluate by the system free energy, which composes mainly chemical free energy, surface energy and elastic strain energy, and its stress dependence was expressed quantitatively by using a relaxation time. The steels used in this study were P91 (9Cr-1Mo-C-N-V-Nb) steel and P92 (9Cr-Mo-W-C-N-V-Nb-B) steel. The obtained results are as follows: (1) the relaxation time of elastic strain energy was expressed as a function of stress and temperature, (2) surface energy of P92 scarcely decreased during creep due to the formation of the Laves phase, and (3) the relaxation time of the chemical free energy in P92 was larger than that in P91.

Topography of the Free Energy Landscape on the Claisen-Schmidt Condensation: Solvent and Temperature Effect in the Rate-Controlling Step

2021 ◽  
Author(s):  
Nayara Dantas Coutinho ◽  
Hugo Gontijo Machado ◽  
Valter Henrique Carvalho-Silva ◽  
Wender A. Silva
Keyword(s):  
Free Energy ◽  
Temperature Effect ◽  
Strong Influence ◽  
Aldol Condensation ◽  
Energy Landscape ◽  
Bond Formation ◽  
Free Energy Landscape ◽  
Rate Controlling Step ◽  
Formation Step

Recent studies have assigned hydroxide elimination and C=C bond formation step in base-promoted aldol condensation the role of having a strong influence in the overall rate reaction, in contrast to...

scholarly journals Catalytic Systems Based on Cp2ZrX2 (X = Cl, H), Organoaluminum Compounds and Perfluorophenylboranes: Role of Zr,Zr- and Zr,Al-Hydride Intermediates in Alkene Dimerization and Oligomerization

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 39
Author(s):  
Lyudmila V. Parfenova ◽  
Pavel V. Kovyazin ◽  
Almira Kh. Bikmeeva ◽  
Eldar R. Palatov
Keyword(s):  
Diffusion Coefficients ◽  
Organoaluminum Compounds ◽  
Zirconium Hydride ◽  
Nmr Studies ◽  
Catalytic Systems ◽  
Selective Formation

The activity and chemoselectivity of the Cp2ZrCl2-XAlBui2 (X = H, Bui) and [Cp2ZrH2]2-ClAlEt2 catalytic systems activated by (Ph3C)[B(C6F5)4] or B(C6F5)3 were studied in reactions with 1-hexene. The activation of the systems by B(C6F5)3 resulted in the selective formation of head-to-tail alkene dimers in up to 93% yields. NMR studies of the reactions of Zr complexes with organoaluminum compounds (OACs) and boron activators showed the formation of Zr,Zr- and Zr,Al-hydride intermediates, for which diffusion coefficients, hydrodynamic radii, and volumes were estimated using the diffusion ordered spectroscopy DOSY. Bis-zirconium hydride clusters of type x[Cp2ZrH2∙Cp2ZrHCl∙ClAlR2]∙yRnAl(C6F5)3−n were found to be the key intermediates of alkene dimerization, whereas cationic Zr,Al-hydrides led to the formation of oligomers.

Fe–N–C Electrocatalysts in the Oxygen and Nitrogen Cycles in Alkaline Media: The Role of Iron Carbide

2021 ◽  
Author(s):  
Tomer Y. Burshtein ◽  
Denial Aias ◽  
Jin Wang ◽  
Matan Sananis ◽  
Eliyahu M. Farber ◽  
...  
Keyword(s):  
Free Energy ◽  
Energy Conversion ◽  
Oxygen Reduction ◽  
Iron Carbide ◽  
Alkaline Media ◽  
Great Promise ◽  
Nitrogen Cycles

Fe–N–C electrocatalysts hold a great promise for Pt-free energy conversion, driving the electrocatalysis of oxygen reduction and evolution, oxidation of nitrogen fuels, and reduction of N2, CO2, and NOx. Nevertheless,...

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