scholarly journals Grain-Boundary Phase Transformation of ZnO:Pr System

2013 ◽  
Vol 19 (S2) ◽  
pp. 1944-1945
Author(s):  
Y. Sato ◽  
J.-Y. Roh ◽  
Y. Ikuhara
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Boundary Phase

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Effect of TiN Addition on the Low Temperature Degradation of Ceramic Tool Materials 3Y-TZP

2006 ◽  
Vol 315-316 ◽  
pp. 40-44 ◽  
Author(s):  
Jing Sun ◽  
Chuan Zhen Huang ◽  
Jun Wang
Keyword(s):  
Phase Transformation ◽  
Elastic Modulus ◽  
Low Temperature ◽  
Grain Boundary ◽  
Volume Expansion ◽  
Monoclinic Phase ◽  
Boundary Phase ◽  
Ceramic Tool ◽  
Tool Materials ◽  
The Stability

Ceramic tool materials, 3Y-TZP added by TiN particles, were fabricated through hot-pressing techniques. The effects of TiN on their low-temperature degradation at 220# in air were investigated. It is shown that TiN can improve the stability of t-ZrO2 and inhibit the transformation from tetragonal to monoclinic phase, and that the content of TiN affects the stability of tetragonal phase and the propagation of tetragonal-to-monoclinic transformation into the specimen interiors. It is suggested that the grain-boundary phase prevents the nucleation of transformation, and that the high elastic modulus of TiN can prevent the propagation of phase transformation by resisting the volume expansion of transformation. When the content of TiN is 20wt%, the ceramic material shows better low temperature degradation resistance.

Grain boundary phase transformation in a CrCoNi complex concentrated alloy

2021 ◽  
pp. 116786
Author(s):  
Fuhua Cao ◽  
Yan Chen ◽  
Shiteng Zhao ◽  
En Ma ◽  
Lanhong Dai
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Boundary Phase

Phase Transformation In Ti-6al-4v Alloys

1972 ◽  
Vol 30 ◽  
pp. 584-585
Author(s):  
Shiro Fujishiro
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Cryogenic Temperature ◽  
Β Phase ◽  
Heat Treated ◽  
Mixed Microstructure ◽  
Ductile Behavior

The Ti-6 wt.% Al-4 wt.% V commercial alloys have exhibited an improved formability at cryogenic temperature when the alloys were heat-treated prior to the tests. The author was interested in further investigating this unusual ductile behavior which may be associated with the strain-induced transformation or twinning of the a phase, enhanced at lower temperatures. The starting materials, supplied by RMI Co., Niles, Ohio were rolled mill products in the form of 40 mil sheets. The microstructure of the as-received materials contained mainly ellipsoidal α grains measuring between 1 and 5μ. The β phase formed an undefined grain boundary around the a grains. The specimens were homogenized at 1050°C for one hour, followed by aging at 500°C for two hours, and then quenched in water to produce the α/β mixed microstructure.

Examination of Fracture Interfaces in Silicon Nitride

1975 ◽  
Vol 33 ◽  
pp. 60-61
Author(s):  
Nancy J. Tighe
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Grain Boundary Sliding ◽  
Boundary Phase ◽  
Turbine Engines ◽  
Boundary Sliding

Silicon nitride is one of the ceramic materials being considered for the components in gas turbine engines which will be exposed to temperatures of 1000 to 1400°C. Test specimens from hot-pressed billets exhibit flexural strengths of approximately 50 MN/m2 at 1000°C. However, the strength degrades rapidly to less than 20 MN/m2 at 1400°C. The strength degradition is attributed to subcritical crack growth phenomena evidenced by a stress rate dependence of the flexural strength and the stress intensity factor. This phenomena is termed slow crack growth and is associated with the onset of plastic deformation at the crack tip. Lange attributed the subcritical crack growth tb a glassy silicate grain boundary phase which decreased in viscosity with increased temperature and permitted a form of grain boundary sliding to occur.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

scholarly journals Optimization of the CCT Curves for Steels Containing Al, Cu and B

2021 ◽  
Author(s):  
Jyrki Miettinen ◽  
Sami Koskenniska ◽  
Mahesh Somani ◽  
Seppo Louhenkilpi ◽  
Aarne Pohjonen ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Austenite Decomposition ◽  
Final Phase ◽  
Cast Irons ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Final Optimization ◽  
Cct Diagrams

AbstractNew continuous cooling transformation (CCT) equations have been optimized to calculate the start temperatures and critical cooling rates of phase formations during austenite decomposition in low-alloyed steels. Experimental CCT data from the literature were used for applying the recently developed method of calculating the grain boundary soluble compositions of the steels for optimization. These compositions, which are influenced by solute microsegregation and precipitation depending on the heating/cooling/holding process, are expected to control the start of the austenite decomposition, if initiated at the grain boundaries. The current optimization was carried out rigorously for an extended set of steels than used previously, besides including three new solute elements, Al, Cu and B, in the CCT-equations. The validity of the equations was, therefore, boosted not only due to the inclusion of new elements, but also due to the addition of more low-alloyed steels in the optimization. The final optimization was made with a mini-tab tool, which discarded statistically insignificant parameters from the equations and made them prudently safer to use. Using a thermodynamic-kinetic software, IDS, the new equations were further validated using new experimental CCT data measured in this study. The agreement is good both for the phase transformation start temperatures as well as the final phase fractions. In addition, IDS simulations were carried out to construct the CCT diagrams and the final phase fraction diagrams for 17 steels and two cast irons, in order to outline the influence of solute elements on the calculations and their relationship with literature recommendations.

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