α/β Phase transformation of silicon nitride: homogeneous and heterogeneous nucleation

1993 ◽  
Vol 12 (24) ◽  
pp. 1937-1939 ◽  
Author(s):  
P. Šajgalík ◽  
D. Galusek
Keyword(s):  
Phase Transformation ◽  
Silicon Nitride ◽  
Heterogeneous Nucleation ◽  
Β Phase

α-β phase transformation of silicon nitride — computer simulation

1991 ◽  
Vol 26 (22) ◽  
pp. 6083-6090 ◽  
Author(s):  
P. Šajgalík
Keyword(s):  
Computer Simulation ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Β Phase

Microstructure in silicon nitride containing β-phase seeding: Part I

1999 ◽  
Vol 14 (7) ◽  
pp. 2966-2973 ◽  
Author(s):  
Horng-Hwa Lu ◽  
Jow-Lay Huang
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Raw Materials ◽  
Aluminum Concentration ◽  
Preparation Technique ◽  
Powder Preparation ◽  
Interfacial Dislocation ◽  
The Core ◽  
Β Phase

A proper powder preparation technique was used to develop elongated β–Si3N4 particles as seeds from raw materials. The phase transformation and development of microstructure in Si3N4 ceramics containing β–Si3N4 seeds were investigated. The specimens of seeded silicon nitride had higher phase transformation rates than the specimens without seed. A core/shell structure was observed by transmission electron microscopy in seeded specimens owing to the difference in aluminum concentration in Si3N4 grains. The misfit between the core and the shell was accommodated by interfacial dislocation that has a rotation character. The growth mode was epitaxial, although there was some compositional difference between the core and the shell. A relatively larger grain size and wider grain size distribution in seeded Si3N4 specimens was due to the amount of β-phase seeds that could act as the nuclei, and the final modification of the microstructure was due to the coalescence process. The crack wake process characterized the mechanism of toughening.

scholarly journals Influence of α to β Phase Transformation on Grain Growth Rate of Silicon Nitride

1997 ◽  
Vol 105 (1222) ◽  
pp. 476-478 ◽  
Author(s):  
Yusuke OKAMOTO ◽  
Naoto HIROSAKI ◽  
Yoshio AKIMUNE ◽  
Mamoru MITOMO
Keyword(s):  
Growth Rate ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Grain Growth ◽  
Β Phase

α/β Phase Transformation in Porous Reaction-Bonded Silicon Nitride Ceramics

2011 ◽  
Vol 194-196 ◽  
pp. 2225-2228
Author(s):  
Jie Xu ◽  
Jun Bo Wang ◽  
Wei Hua Cui ◽  
Xiao Lei Su ◽  
Wan Cheng Zhou
Keyword(s):  
Dielectric Constant ◽  
Phase Transformation ◽  
Dielectric Properties ◽  
Silicon Nitride ◽  
Dielectric Loss ◽  
Point Defects ◽  
Nitriding Temperature ◽  
Β Phase ◽  
Nitride Ceramics ◽  
Tan Δ

Porous reaction-bonded silicon nitride ceramics with different values of α/β ratio were obtained by setting the nitriding temperature and time. The influence of α/β phase transformation on the dielectric properties of porous silicon nitride ceramics has been investigated. The results show that the α/β transformation occurs when the nitriding temperature is higher than 1400°C . The values of α/β ratio decrease with increase of nitriding temperature and time. The dielectric constant ε′ and the dielectric loss tan δ of the samples increase because of the α/β transformation, and the change of the dielectric loss is more obvious. The increase of concentrations of point defects due to the α/β transformation leads to the significant increase of the dielectric loss.

On the α-to-β phase transformation in silicon nitride

1988 ◽  
Vol 105-106 ◽  
pp. 151-159 ◽  
Author(s):  
V.K Sarin
Keyword(s):  
Phase Transformation ◽  
Silicon Nitride ◽  
Β Phase

Densification and α/β Phase Transformation of SHS Si3N4 Containing Al2O3 and Y2O3 during Sintering

2007 ◽  
Vol 561-565 ◽  
pp. 577-580 ◽  
Author(s):  
Ling Bai ◽  
Chang Chun Ge ◽  
Wei Ping Shen ◽  
Ke Zhang ◽  
X.D. Mao
Keyword(s):  
Phase Transformation ◽  
Silicon Nitride ◽  
Precipitation Process ◽  
Main Role ◽  
Nitride Powder ◽  
Densification Process ◽  
Β Phase ◽  
Α Phase ◽  
Silicon Nitride Powder ◽  
Si3n4 Ceramics

The densification and phase transformation of high α-phase silicon nitride powder synthesized by SHS with a combination of Y2O3 and Al2O3 sintering additives were investigated. The densification process occurred rapidly from 1400 to 1500 °C and was nearly finished at 1500 °C. However, the α-β transformation of silicon nitride progressed rapidly from 1500 to 1600 °C, and completed at 1600 °C. The phase transformation of silicon nitride lagged behind the densification of Si3N4 ceramics. It showed that the solution and precipitation process did not play the main role in the densification of silicon nitride. The sufficient amount of liquid phase was crucial to complete the densification.

Effect of microwave heating on densification and α → β phase transformation of silicon nitride

1997 ◽  
Vol 17 (13) ◽  
pp. 1625-1630 ◽  
Author(s):  
Yoon Chang Kim ◽  
Chong Hee Kim ◽  
Do Kyung Kim
Keyword(s):  
Phase Transformation ◽  
Silicon Nitride ◽  
Microwave Heating ◽  
Β 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.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

γ→β phase transformation in Ti-42.9Al-4.6Nb–2Cr

2021 ◽  
Vol 133 ◽  
pp. 107169
Author(s):  
R.R. Xu ◽  
M.Q. Li
Keyword(s):  
Phase Transformation ◽  
Β Phase
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