Influence of Mn Additions on the Thermoelastic and Pseudoelastic Behaviour of Cu-Ai-Ni Alloys

1994 ◽  
Vol 360 ◽  
Author(s):  
M.A. Morris ◽  
T. Lipe
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Activation Energies ◽  
Manganese Concentration ◽  
Ni Alloys ◽  
Two Phases ◽  
Mn Additions ◽  
Kinetics Of

AbstractThe transformation properties of Cu-Al-Ni alloys modified by the additions of boron and manganese have been interpreted by studying the reversibility and stability of the martensitic transformation as a function of heat treatment and of manganese concentration between 2 and 4 wt%. The alloy containing 2% Mn exhibits a lack of thermoelasticity due to a decrease of the degree of B2 order and supression of DO3 order during quenching and the increase of both types of order during annealing. From the determination of the activation energies responsible for the martensitic and reverse transformations, we have deduced that, in both cases, the kinetics of the transformation are controlled by an atomic jump at the interface between the two phases.

Hydrogen Passivation Kinetics of Si Nanocrystals in SiO2

2003 ◽  
Vol 770 ◽  
Author(s):  
Andrew R. Wilkinson ◽  
Robert G. Elliman
Keyword(s):  
Reaction Kinetics ◽  
Activation Energies ◽  
Hydrogen Passivation ◽  
Time Resolved ◽  
Luminescence Efficiency ◽  
Si Nanocrystals ◽  
Preliminary Study ◽  
Kinetics Of ◽  
Insight Into

AbstractHydrogen passivation of non-radiative defects increases the luminescence intensity from silicon nanocrystals. In this study, photoluminescence (PL) and time-resolved PL were used to investigate the chemical kinetics of the hydrogen passivation process. Isochronal and isothermal annealing sequences were used to determine the reaction kinetics for the absorption and desorption of hydrogen, using the generalised consistent simple thermal (GST) model proposed by Stesmans for Pb defects at planar Si/SiO2 interfaces. This included determination of the activation energies and rate constants for the forward and reverse reactions as well as the associated spread in activation energies. The reaction kinetics determined from such measurements were found to be in excellent agreement with those for the passivation of Pb defects at planar Si/SiO2 interfaces, suggesting the nanocrystal emission process is also limited by such defects. These results provide useful model data as well as insight into the processing conditions needed to achieve optimum passivation in H2. As an extension to the work, a preliminary study into passivation by atomic hydrogen was pursued via a post-metallization Al anneal (alneal). A considerable gain in luminescence efficiency was achieved over the previously optimised passivation in H2.

scholarly journals Microstructure, hardness and interfacial energy in Co-9Al-10W-xNi (x=15, 25, 35 at. %) alloys during aging

2017 ◽  
Vol 53 (3) ◽  
pp. 303-308 ◽  
Author(s):  
C. Che ◽  
S. Yang ◽  
M. Wei ◽  
L. Zhang ◽  
Q. Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Interfacial Energy ◽  
Aging Temperature ◽  
Volume Fraction ◽  
Ni Alloys ◽  
Interfacial Energies ◽  
Ni Content ◽  
Coarsening Kinetics ◽  
The Relationship ◽  
Kinetics Of

In the present paper, three Co-Al-W-Ni alloys (i.e., Co-9Al-10W-xNi with x=15, 25, 35 at. %) and their heat treatment mechanisms were carefully designed on the basis of the available phase equilibrium information. The temporal evolution of the microstructure and hardness in the Co-9Al-10W-xNi (x=15, 25, 35) alloys during aging process was measured, from which the effect of additional Ni contents, aging temperature and time on microstructure and hardness in the three Co-Al- W-Ni alloys was analyzed. Considering that the alloy compositions and heat treatment are not directly related with the hardness, the relationship between hardness and microstructure was then linked. It was found that the hardness of Co-based superalloys increases as the volume fraction of ?' precipitates increases, while decreases with the increase of the radius and interval of ?' precipitates. Moreover, the interfacial energy of ?/?' interface was also evaluated on the basis of the coarsening kinetics of ?' precipitates and the Philippe-Voorhees model in combination with the thermodynamic and atomic mobility databases. The results indicate that the interfacial energies of ?/?' interface reduce as the increase of additional Ni content and aging temperature.

scholarly journals Determination of hyperfine fields and atomic ordering in NiMnFeGe exhibiting martensitic transformation

Nukleonika ◽  
2015 ◽  
Vol 60 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Dariusz Satuła ◽  
Krzysztof Szymański ◽  
Katarzyna Rećko ◽  
Wojciech Olszewski ◽  
Beata Kalska-Szostko
Keyword(s):  
Martensitic Transformation ◽  
Room Temperature ◽  
Paramagnetic State ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Atomic Ordering ◽  
Hyperfine Fields ◽  
X Ray ◽  
Two Phases

Abstract The hyperfine fields and atomic ordering in Ni1−xFexMnGe (x = 0.1, 0.2, 0.3) alloys were investigated using X-ray diffraction and Mössbauer spectroscopy at room temperature. The X-ray diffraction measurements show that the samples with x = 0.2, 0.3 crystallized in the hexagonal Ni2In-type of structure, whereas in the sample with x = 0.1, the coexistence of two phases, Ni2In- and orthorhombic TiNiSi-type of structures, were found. The Mössbauer spectra measured with x = 0.2, 0.3 show three doublets with different values of isomer shift (IS) and quadrupole splitting (QS) related to three different local surroundings of Fe atoms in the hexagonal Ni2In-type structure. It was shown that Fe atoms in the hexagonal Ni2In-type structure of as-cast Ni1−xFexMnGe alloys are preferentially located in Ni sites and small amount of Fe is located in Mn and probably in Ge sites. The spectrum for x = 0.1 shows the doublets in the central part of spectrum and a broad sextet. The doublets originate from the Fe atoms in the paramagnetic state of hexagonal Ni2In-type structure, whereas the sextet results from the Fe atoms in orthorhombic TiNiSi-type structure.

Annealing Kinetics of Neutron?Irradiated Aluminium and Copper

1960 ◽  
Vol 13 (2) ◽  
pp. 347 ◽  
Author(s):  
TH Blewitt ◽  
RR Coltman ◽  
CE Klabunde
Keyword(s):  
Activation Energy ◽  
Activation Energies ◽  
Slope Method ◽  
Measured Activation Energy ◽  
Measured Activation ◽  
Kinetics Of ◽  
Constant Activation Energy

Activation energies for the annealing of copper and aluminium following reactor bombardment near 4 OK have been measured in the range from 10 to 40 OK. Both the change in slope method and the isothermal technique method were utilized with the assumption that a constant activation energy existed. Computations of the number of jumps involved from the measured activation energy result in an impossibly small number. It is obvious that the method for determination of the activation energies is not applicable, probably because of the non-uniqueness of the activation energy.

Effect of Heat Treatment Conditions on Multistage Martensitic Transformation in Aged Ni-rich Ti-Ni Alloys

2004 ◽  
Vol 842 ◽  
Author(s):  
Minoru Nishida ◽  
Toru Hara ◽  
Yasuhiro Morizono ◽  
Mitsuhiro Matsuda ◽  
Kousuke Fujishima
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Quartz Tube ◽  
Preferential Oxidation ◽  
Ni Alloys ◽  
Treatment Conditions ◽  
Precipitation Morphology

ABSTRACTIt has been demonstrated with systematic experiments that the appearance and disappearance of multistage martensitic transformation (MMT) in aged Ni-rich Ti-Ni alloys depend on the heat treatment conditions. No multistage transformation occurs when the evaporation of Ti and Ni and/or the preferential oxidation of Ti in the specimen are prevented and the purification of heat treatment atmosphere in an evacuated quartz tube is achieved. The heterogeneity in precipitation morphology of the Ti3Ni4 phase, which is responsible for the multistage transformation can be suppressed with the regulation of heat treatment atmosphere as mentioned above. We have concluded that the multistage martensitic transformation in aged Ni-rich Ti-Ni alloys is extrinsic in nature, and is an artifact during the heat treatment.

Effect of heat treatment atmosphere on the multistage martensitic transformation in aged Ni-rich Ti–Ni alloys

2006 ◽  
Vol 438-440 ◽  
pp. 489-494 ◽  
Author(s):  
K. Fujishima ◽  
M. Nishida ◽  
Y. Morizono ◽  
K. Yamaguchi ◽  
K. Ishiuchi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Ni Alloys
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