Effect of grain size on phase stability of monoclinic U–Nb alloy during low-temperature aging

2015 ◽  
Vol 465 ◽  
pp. 167-169 ◽  
Author(s):  
Yanzhi Zhang ◽  
Xinjian Zhang ◽  
Xianglin Chen ◽  
Guan Weijun ◽  
Xiaolin Wang
Keyword(s):  
Grain Size ◽  
Low Temperature ◽  
Phase Stability ◽  
Low Temperature Aging ◽  
Temperature Aging

Mechanical properties and low-temperature aging of tetragonal zirconia polycrystals processed by hot isostatic pressing

2003 ◽  
Vol 18 (10) ◽  
pp. 2415-2426 ◽  
Author(s):  
J. Muñoz-Saldaña ◽  
H. Balmori-Ramírez ◽  
D. Jaramillo-Vigueras ◽  
T. Iga ◽  
G. A. Schneider
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Low Temperature ◽  
Hot Isostatic Pressing ◽  
Tetragonal Zirconia ◽  
Hot Water ◽  
Full Density ◽  
Isostatic Pressing ◽  
Low Temperature Aging ◽  
Temperature Aging

The influence of grain size and density of yttria-tetragonal zirconia polycrystals (Y-TZPs) ceramics on mechanical properties and on low-temperature aging degradation (LTD) in air and in hot water was investigated. A TZP powder containing 3 mol% Y2O3 was consolidated by slip casting and densified by the sintering/hot isostatic pressing (HIP) method. Only the presintered samples that contained less than 0.15% open porosity reached near full density after HIP. The best conditions to reach full density were found to be attained by presintering and HIP both at 1400 °C. At these conditions, some of the best mechanical properties such as modulus of rupture and Weibull modulus reached 1397 ± 153 MPa and, 10.6, respectively. These values were clearly higher than those obtained from sintered bodies and samples hot isostatically pressed at 1600 °C. Aging degradation of 3Y-TZP materials can be avoided through microstructural design. Fully dense materials with a critical grain size <0.36 μm did not show any evidence of degradation after extreme aging conditions at pressurized autoclaving in hot water at 100, 200, and 260 °C for 8 h. We propose a criterion to predict degradation in air as well as in hot water for the characterized materials based on the microstructure and density control of the samples.

Effect of Low-Temperature Aging on Thermally-Induced Phase Transformation of NiTi Wire with a Wide Range of Grain Sizes

2021 ◽  
Vol 1042 ◽  
pp. 9-16
Author(s):  
Zhi Hao Zhao ◽  
Jian Ping Lin ◽  
Jun Ying Min ◽  
Yong Hou ◽  
Bo Sun
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Low Temperature ◽  
Thermally Induced ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Wide Range ◽  
Low Temperature Aging ◽  
Niti Wires ◽  
Temperature Aging

Thermally-induced phase transformation (PT) is of significance and value to the application of NiTi alloy components. Low-temperature aging (LTA) treatment was used to alter PT characteristics of NiTi alloys avoiding undesirable grain growth. Effect of LTA on PT of NiTi wires with a wide range of grain sizes from 34 nm to 8021 nm was investigated in this study. As the average grain size varies from 34 to 217 nm, the temperature of the B2↔R transformation increase as a result of LTA, and the increasing effect is more obvious at a larger grain size. For NiTi alloys with average grain sizes ranging from 523 to 1106 nm, transformation sequence changes from B2↔B19' to B2↔R due to LTA. For the sample with an average grain size of 2190 nm, the B2↔B19' transformation is replaced by B2↔R←B19' after LTA. When the average grain size is larger than 2190 nm, transformation sequence changes from B2↔B19' to B2↔R↔B19' after LTA. Transmission emission microscope observations reveal that the above-mentioned PT behavior correlates with the coupled effect of grain size and precipitation. The precipitation of Ni4Ti3 in the grains with a size smaller than ~150 nm is inhibited after LTA, the temperature of B2→R of samples with average GS smaller than ~150 nm still is elevated due to the inhomogeneous grain size of NiTi wires.

scholarly journals The effect of low temperature aging on the mechanical property & phase stability of Y-TZP ceramics

2009 ◽  
Vol 1 (3) ◽  
pp. 113 ◽  
Author(s):  
Hyung-Tae Kim ◽  
Jung-Suk Han ◽  
Jae-Ho Yang ◽  
Jai-Bong Lee ◽  
Sung-Hun Kim
Keyword(s):  
Mechanical Property ◽  
Low Temperature ◽  
Phase Stability ◽  
Low Temperature Aging ◽  
Temperature Aging

Relationship between Surface Residual Stress Fields and Hydrothermal Environment on Low Temperature Aging of 3Y-TZP

2007 ◽  
Vol 361-363 ◽  
pp. 755-758
Author(s):  
Junji Ikeda ◽  
Fumiaki Miyaji ◽  
Masaru Ueno ◽  
Giuseppe Pezzotti
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Low Temperature ◽  
Phase Stability ◽  
Surface Condition ◽  
Stress Fields ◽  
Material Surface ◽  
Aging Test ◽  
Low Temperature Aging ◽  
Temperature Aging

Phase stability of 3 mol% yttria stabilized polycrystalline zirconia ceramics (3Y-TZP) was evaluated by aging test in water vapor environment and Raman spectroscopic technique. In our previous study, it has been confirmed that phase stability was improved by controlling sintering temperature. In this study, we pointed our attention and evaluated the influence of surface conditions related to machining and to heat treatment, thus monitoring the changes in phase transformation fraction and residual stress on the material surface. From the results of aging test, an increase in monoclinic fraction was observed for grinded surfaces as compared with polished surfaces. Samples subjected to heat treatment after machining showed improved phase stability. A Vickers indentation print was also introduced on a 3Y-TZP surface, and the relationship between surface condition and low temperature aging was evaluated in the neighborhood of the print. We found that the residual stress fields induced in phase-transformed areas were enhanced during low temperature aging, and that phase stability was improved by heat treatment.

CAD/CAM Zirconia for Dental Application

2013 ◽  
Vol 320 ◽  
pp. 505-511
Author(s):  
Ning Li ◽  
Zhi Kai Wu ◽  
Chao Jian ◽  
Wan Qian Zhao ◽  
Jia Zhen Yan
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Key Words ◽  
20Th Century ◽  
Dental Materials ◽  
Tetragonal Zirconia ◽  
Dental Application ◽  
Cad Cam ◽  
Low Temperature Aging ◽  
Temperature Aging

During the 20th century, both dental materials and dental technologies for the fabrication of dental prosthesis progressed remarkably. Owing to the increased demand of safety and aesthetics, 3 mol% yttria stabilized tetragonal zirconia polycrystalline has been recently introduced in prosthetic dentistry for the fabrication of crowns and fixed partial dentures, in combination with CAD/CAM technique. This greatly changed the conventional dental laboratory work which is labor-intensive and experience-dependent. This review mainly introduced the state of dental zirconia and the application of CAD/CAM technology in dentistry. Key words: Dental Zirconia; CAD/CAM Technique; Mechanical Properties; Transformation Toughing; Low Temperature Aging;

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