scholarly journals Atomic study on phase transformation of the strengthening phase in a die-casting Mg−Al−La alloy via an intermediate phase

2021 ◽  
pp. 109904
Author(s):  
Shuhui Lv ◽  
Fanzhi Meng ◽  
Qiang Yang ◽  
Kai Guan ◽  
Jian Meng
Keyword(s):  
Phase Transformation ◽  
Intermediate Phase ◽  
Die Casting ◽  
Strengthening Phase

Hydrothermal Synthesis and Phase Formation Mechanism of TiO2(B) Nanorods via Alkali Metal Titanate Phase Transformation

2018 ◽  
Vol 283 ◽  
pp. 23-36 ◽  
Author(s):  
Yothin Chimupala ◽  
Rik Drummond-Brydson
Keyword(s):  
Phase Transformation ◽  
Intermediate Product ◽  
Intermediate Phase ◽  
Metastable Phase ◽  
Exchange Process ◽  
Titanium Isopropoxide ◽  
Growth Direction ◽  
Proton Exchange ◽  
Transformation Mechanism ◽  
Synthesis Conditions

Titanium dioxide (B phase) with 1-D structures was successfully fabricated via a hydrothermal method with a subsequent ion-exchange process and calcination. P25, titanium isopropoxide (TTIP), rutile and also anatase were used as Ti precursors in the alkali hydrothermal system. TTIP promoted an elongation of nanorod morphology whereas the other precursors produced short nanorod structures. The different types of titanium precursors did not have any influence on the phase transformation during the fabrication process. Na2Ti6O13 was the primary intermediate product after washing the hydrothermal sample. H2Ti3O7 was the secondary intermediate phase obtained following proton-exchange of Na2Ti6O13 in HNO3 solution. Finally, the TiO2(B) phase was the product of calcination of the secondary intermediate product at 400°C for 5 hr. A phase transformation mechanism is presented based on an investigation of products at each of the steps. The effects of the synthesis conditions on tailoring of the crystal morphology are discussed. The growth direction of the TiO2(B) nanorods was investigated by HR-TEM and SADP. Finally, the metastable phase of TiO2(B) was shown to be transformed to anatase during thermal treatment at temperatures higher than 400°C.

Constructing a compact heterojunction structure of Ag2CO3/Ag2O in-situ intermediate phase transformation decorated on ZnO with superior photocatalytic degradation of ibuprofen

2020 ◽  
Vol 251 ◽  
pp. 117391 ◽  
Author(s):  
Nurafiqah Rosman ◽  
Wan Norharyati Wan Salleh ◽  
Mohamad Azuwa Mohamed ◽  
Zawati Harun ◽  
Ahmad Fauzi Ismail ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Photocatalytic Degradation ◽  
Intermediate Phase ◽  
Heterojunction Structure

Phenomena And Mechanism On Phase Transformation Twinning In Nanocrystalline BaTiO3

2010 ◽  
Vol 1256 ◽  
Author(s):  
Sujata Mazumder ◽  
Jiten Ghosh
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
High Temperature ◽  
Intermediate Phase ◽  
High Vacuum ◽  
Point Group ◽  
Atomic Scale ◽  
Twin Structure ◽  
High Temperature Xrd ◽  
Low Symmetry

AbstractThe detailed structure of nanocrystalline BaTiO3 powder during ball milling has been studied using XRD & TEM. The study illustrates important advances in understanding atomic scale properties of this material. Ferroelectric BaTiO3 powder undergoes phase transformation along the sequence Cubic(Pm3m)-tetragonal(P4mm)-orthohombic (Amm2)-rhombohedral(R3m) structure when pressureless sintered samples are cooled from high temperature to low temperature. The high to low symmetry phases are not related to group subgroup symmetry as transformation is discontinuous and first order in nature and the twin relationship in the low symmetry is forbidden by Landau theory. In case of ball milled BaTiO3 powder a continuous and diffusionless phase transition occur via second order to and from a metastable intermediate phase. In this pathway crystallites in the aggregation are twinned and the twin structure is related to crystal point group m3m which in the present case is illustrated as having 6mm symmetry formed under low driving force. The unit cell evolution due to phase transition and the crystallographic relationship are established. The phase transformation, coalescence and twin structure of thermally annealed BaTiO3 nanocrystals under high vacuum has been investigated using in situ high temperature XRD. The structure analysis is performed with the use of the method of computer modelling of disorder structure and simulation of corresponding diffraction pattern.

Phase Transformation of MgAlON-SiAlON Powders Synthesized by Carbothermal Reduction-Nitridation from Ludwigite Tailings

2013 ◽  
Vol 365-366 ◽  
pp. 1095-1099
Author(s):  
Tao Jiang ◽  
Lu Zhang ◽  
Yi Tang ◽  
Yi Xia ◽  
Xiang Xin Xue
Keyword(s):  
Phase Transformation ◽  
Optimal Condition ◽  
Carbothermal Reduction ◽  
Intermediate Phase ◽  
Xrd Analysis ◽  
Synthesis Temperature ◽  
Holding Time ◽  
Experimental Results ◽  
Crystalline Phases ◽  
Influence Of Temperature

This paper focuses on the influence of temperature and holding time on synthesizing MgAlON-SiAlON powders applying CRN method. The results were analyzed by chemical and XRD analysis technology. The experimental results revealed that β-SiAlON, as an intermediate phase, appeared in the synthesized products at 1200°C. With the increase of synthesis temperature, β-SiAlON was translated into Mg-SiAlON polytypoid (Mg1.25Si1.25Al2.5O3N3) and reached the maximum at 1450°C. Increasing synthesis temperature was beneficial to generate MgAlON, and the optimal condition of temperature for powders synthesis was 1500°C. β-SiAlON disappeared with the increase of holding time. MgAlON and Mg-SiAlON polytypoid became the main crystalline phases with a holding time of 4h. Whats more, the phase compositions had no evident change with longer holding time. Flaky MgAlON grains and elongated Mg-SiAlON grains were observed in synthesized powders.

scholarly journals Interphase boundary segregation induced phase transformation in a high-pressure die casting Mg-Al-La-Ca-Mn alloy

2020 ◽  
Vol 190 ◽  
pp. 108566 ◽  
Author(s):  
Qiang Yang ◽  
Shuhui Lv ◽  
Pengfei Qin ◽  
Fanzhi Meng ◽  
Xin Qiu ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Interphase Boundary ◽  
Die Casting ◽  
Boundary Segregation ◽  
High Pressure Die Casting ◽  
Pressure Die Casting

Precipitate Processes in Mg-5Al Magnesium Alloy

2012 ◽  
Vol 191 ◽  
pp. 131-136 ◽  
Author(s):  
Andrzej Kiełbus
Keyword(s):  
Solid Solution ◽  
Magnesium Alloy ◽  
Die Casting ◽  
Sand Casting ◽  
Grain Refining ◽  
Strengthening Phase ◽  
The Impact

In this article, the impact of long-term annealing on transformation of microstructure, in sand casting and die-casting Mg-5Al magnesium alloy was discussed. The Mg17Al12 phase of the diverse morphology is the basic strengthening phase in Mg-5Al alloys. After sand casting microstructure of Mg-5Al alloy consists of α-Mg solid solution with continuous and discontinuous precipitates of Mg17Al12 phase. After die-casting, the structure is characterized by significant grain refining of α-Mg solid solution, however Mg17Al12 phase, together with α-Mg solid solution, forms fully divorced eutectic. The Mg17Al12 phase undergo decomposition and coagulation at the temperature above 180°C and higher.

The intermediate phase during (Bi,Pb)2Sr2CaCu2O8+δ to (Bi,Pb)2Sr2Ca2Cu3O10+δ phase transformation

1995 ◽  
Vol 248 (1-2) ◽  
pp. 119-126 ◽  
Author(s):  
Weimin Bian ◽  
Yimei Zhu ◽  
Y.L. Wang ◽  
M. Suenaga
Keyword(s):  
Phase Transformation ◽  
Intermediate Phase ◽  
Δ Phase
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