Oxidation Behavior and Subsurface Phase Transformation of Novel High Mn Cryogenic Steel during Heat Treatment

2020 ◽  
Vol 91 (4) ◽  
pp. 1900555
Author(s):  
Yu Liu ◽  
Yong Wang ◽  
Guangqiang Li ◽  
Huan Cai ◽  
Honghong Wang ◽  
...  
1992 ◽  
Vol 7 (11) ◽  
pp. 3065-3071 ◽  
Author(s):  
Peir-Yung Chu ◽  
Isabelle Campion ◽  
Relva C. Buchanan

Phase transformation and preferred orientation in ZrO2 thin films, deposited on Si(111) and Si(100) substrates, and prepared by heat treatment from carboxylate solution precursors were investigated. The deposited films were amorphous below 450 °C, transforming gradually to the tetragonal and monoclinic phases on heating. The monoclinic phase developed from the tetragonal phase displacively, and exhibited a strong (111) preferred orientation at temperature as low as 550 °C. The degree of preferred orientation and the tetragonal-to-monoclinic phase transformation were controlled by heating rate, soak temperature, and time. Interfacial diffusion into the film from the Si substrate was negligible at 700 °C and became significant only at 900 °C, but for films thicker than 0.5 μm, overall preferred orientation exceeded 90%.


Author(s):  
Abhijit Biswas ◽  
Suman Kalyan Das ◽  
Prasanta Sahoo

The microstructural changes of electroless Ni–P–Cu coating at various heat-treatment conditions are investigated to understand its implications on the tribological behavior of the coating. Coatings are heat-treated at temperatures ranging between 200°C and 800 °C and for 1–4 h duration. Ni–P–Cu coatings exhibit two-phase transformations in the temperature range of 350–450 °C and the resulting microstructural changes are found to significantly affect their thermal stability and tribological attributes. Hardness of the coating doubles when heat-treated at 452 °C, due to the formation of harder Ni3P phase and crystalline NiCu. Better friction and wear performance are also noted upon heat treatment of the coating at the phase transformation regime, particularly at 400 °C. Wear mechanism is characterized by a mixed adhesive cum abrasive wear phenomena. Heat treatment at higher temperature (600 °C and above) and longer duration (4 h) results in grain coarsening phenomenon, which negatively influences the hardness and tribological characteristics of the coating. Besides, diffusion of iron from the ferrous substrate as well as greater oxide formation are noticed when the coating is heat-treated at higher temperatures and for longer durations (4 h).


2006 ◽  
Vol 512 ◽  
pp. 111-116 ◽  
Author(s):  
Yuki Matsuoka ◽  
Kazuyoshi Chikugo ◽  
Takakazu Suzuki ◽  
Yasuo Matsunaga ◽  
Shigeji Taniguchi

Ru coating prior to aluminizing is one of the effective methods to reduce the harmful intermediate layer that forms under the coating (SRZ) on a 4th generation Ni-base SC superalloy. This study examined the short-term isothermal oxidation behavior of this Ru-modified coating at 1373 K in air. Surface observation by SEM showed that the scale becomes flat and uniform in comparison to simple aluminide coating. XRD and cross-sectional analysis results also showed that phase transformation from β-NiAl to γ’-Ni3Al seldom occurs in the Ru-modified coating layer leading to the prevention of local oxidation.


2021 ◽  
Vol 1036 ◽  
pp. 20-31
Author(s):  
Jun Jie Ye ◽  
Zhi Rong He ◽  
Kun Gang Zhang ◽  
Yu Qing Du

Ti-Ni based shape memory alloys (SMAs) are of excellent shape memory effect, superelasticity and damping property. These properties of the alloys can be fully displayed only after proper heat treatment. In this paper, the research progresses of the effect of the heat treatment on the microstructure, phase composition, phase transformation behaviors and shape memory properties in Ti-Ni based SMAs are reviewed, the correlation influence mechanism is summarized, and the future research directions in this field are pointed out. It is expected to provide reference for the development of Ti-Ni based SMAs and their heat treatment technologies.


1998 ◽  
Vol 524 ◽  
Author(s):  
S. J. Doh ◽  
J. M. Lee ◽  
D. Y. Noh ◽  
J. H. Je

ABSTRACTThe surface-front oxidation mechanism of iron was investigated by time-resolved, glancingangle Fe K-edge fluorescence EXAFS measurements at various oxidation temperatures of 200-700 C. The glancing angle was chosen according to the depth of the oxide layer, roughly 1500-2000A. The oxidation behavior under rapid heating(up to 600°C within 10 minutes) was compared with the slowly heated oxidation process using the Quick-EXAFS measurements. In the slowly heated process, Fe3O4 was the dominating phase at a relatively low temperature (300-400 C) initially. However, at a relatively high temperature (above 600°C), the Fe2O3 and FeO crystalline phases are gradually enriched as the successive oxidation process involving intrusive oxygen proceeded. Remarkably under a prolonged heat treatment above 600°C, the stable FeO phase that exists in a deep-lying interface structure and Fe2O3 phase eventually dominates the thick front-surface structure. In a quickly heated process, however, Fe3O4 phase is less dominating, which is contradictory to the commonly accepted oxidation models. The EXAFS results are discussed in conjunction with the x-ray diffraction features under the same heat treatment conditions.


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