Properties of ZrO2–Al2O3 composite as a function of isothermal holding time

2007 ◽  
Vol 25 (5-6) ◽  
pp. 374-379 ◽  
Author(s):  
J.K.M.F. Daguano ◽  
C. Santos ◽  
R.C. Souza ◽  
R.M. Balestra ◽  
K. Strecker ◽  
...  
Keyword(s):  
Isothermal Holding ◽  
Holding Time ◽  
Al2o3 Composite

Temperature-induced structural transition of ceria by bulk reduction under hydrogen atmosphere

CrystEngComm ◽  
2018 ◽  
Vol 20 (31) ◽  
pp. 4359-4363 ◽  
Author(s):  
Takeshi Matsukawa ◽  
Akinori Hoshikawa ◽  
Toru Ishigaki
Keyword(s):  
High Temperature ◽  
Structural Transition ◽  
Isothermal Holding ◽  
Hydrogen Atmosphere ◽  
Holding Time

Ceria (CeO2) was kinetically reduced in hydrogen depending on the isothermal holding time at high temperature.

Effect of isothermal process parameters on semi-solid microstructure of chip-based Al–Cu–Mn–Ti alloy prepared by SIMA method

2020 ◽  
Vol 34 (33) ◽  
pp. 2050385
Author(s):  
Ye Wang ◽  
Maoliang Hu ◽  
Hongyu Xu ◽  
Zesheng Ji ◽  
Xuefeng Wen ◽  
...  
Keyword(s):  
Process Parameters ◽  
Ostwald Ripening ◽  
Isothermal Holding ◽  
Treatment Temperature ◽  
Holding Time ◽  
Isothermal Treatment ◽  
Isothermal Process ◽  
Semi Solid ◽  
Average Size ◽  
Relationship Of

A typical Al–Cu–Mn–Ti aluminum alloy chip was adopted to prepare semi-solid billets by a Strain-Induced Melt Activation (SIMA) method, and the effects of isothermal process parameters on the semi-solid microstructure evolution of the alloy were investigated in this work. The result showed that semi-solid billets with highly spheroidal and homogeneous fine grains could be prepared from chips by the SIMA method. With the increase of isothermal temperature, the finer and near-spherical grains are obtained, the grains coarsen and became ellipse at 903 K because of the coarsening mechanisms of coalescence and Ostwald ripening. The relationship of isothermal holding time and grains size followed the LSW theory well, and more spherical microstructure can be brought by prolonging the holding time until 3000 s. Thus, the optimal isothermal treatment temperature is 893 K and holding time is 3000 s, the corresponding average size and roundness of grains are 137 [Formula: see text]m and 1.108, respectively.

Effects of SiC Particle and Holding Time on Semi-Solid Microstructure of SiCP/AZ61 Composites

2010 ◽  
Vol 152-153 ◽  
pp. 628-633
Author(s):  
Fa Yun Zhang ◽  
Jian Xiong Ye ◽  
Hong Yan
Keyword(s):  
Heat Treatment ◽  
Microstructure Evolution ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Isothermal Holding ◽  
Holding Time ◽  
Isothermal Heat Treatment ◽  
Particle Volume ◽  
Semi Solid ◽  
Sic Particle

Effects of SiC particle and holding time on microstructure evolution of SiCP/AZ61 composites during semi-solid isothermal heat treatment method were studied, and evolution mechanism of semi-solid microstructure of composites was discussed. The results indicated that the process of microstructure evolution of SiCP/AZ61 composites by the isothermal holding at the temperatures of 595°C for different times (0min~90min) experienced in succession the rapid merging of the secondary dendritic arms →large massive structure→melting and separating of the local grain boundary →spheroidization of the gains →slowing growth of globular microstructure. Synthetically, after isothermal holding at 595°C for 30min to 60min the favorable semi-solid microstructure can be obtained; Compared with the monolithic AZ61alloy, microstructure of SiCP/AZ61 composites during semi-solid isothermal heat-treatment was finer as a result of entering of Sic particle, and with the increasing of SiC particle volume fraction, globular gain size was smaller.

Microstructural Evolution of AZ31 Mg Wrought Alloy during Partial Remelting for Thixoextrusion

2006 ◽  
Vol 116-117 ◽  
pp. 251-254
Author(s):  
Young Ok Yoon ◽  
Shae K. Kim
Keyword(s):  
Grain Size ◽  
Microstructural Evolution ◽  
Liquid Fraction ◽  
Isothermal Holding ◽  
Holding Time ◽  
Interesting Point ◽  
Grain Sizes ◽  
Partial Remelting ◽  
Average Grain Size ◽  
Holding Temperature

An attempt has been made to investigate feasibility of thixoextrusion for AZ31 Mg wrought alloy through simple partial remelting. Microstructural evolution of AZ31 Mg wrought alloy for thixoextrusion was investigated as functions of isothermal holding temperature and time in the partially remelted semisolid state. The interesting point of this study was that the thixotropic structures of AZ31 Mg wrought alloy without additional pretreatment could be obtained through simple partial remelting. The uniform average grain size and liquid fraction according to the isothermal holding time were very important for the thixoextrusion. Because, it is must be considered on actual extrusion time. The liquid fraction was increased with increasing isothermal holding temperature and time. But, the liquid fraction was almost uniform after 10 min. The average grain size was decreased with increasing isothermal holding temperature. On the other hand, as the holding time increased, the average grain sizes were uniform at 615 and 622. This phenomenon is very useful for thixoextrusion in terms of process control such as actual extrusion time.

scholarly journals Identification of Precipitates in Cr-Mn-N Based Steel After Thermal Exposures

2014 ◽  
Vol 22 (34) ◽  
pp. 51-57
Author(s):  
Michal Ondruška ◽  
Mária Dománková ◽  
Miroslav Jáňa ◽  
Milan Marônek
Keyword(s):  
Grain Boundaries ◽  
Isothermal Annealing ◽  
Discontinuous Precipitation ◽  
Isothermal Holding ◽  
Steel Structure ◽  
Thermal Exposure ◽  
Holding Time ◽  
Secondary Phases ◽  
Σ Phase ◽  
Annealing Twins

Abstract The paper deals with the identification of precipitates in the Cr-Mn-N steels after thermal exposure. The purpose of the study is to clarify the M2N precipitation by isothermal annealing at the temperatures of 750 and 900 °C with a holding time of 5, 10, 30 min, 1 hr. and 10 hrs. Microstructure of austenitic steel was characterised by the typical presence of annealing twins. Stepwise etching was observed at the holding time of 5 and 10 minutes, but at the holding time of 30 minutes, secondary particles were precipitated at the grain boundaries. Corrosion tests revealed that holding time significantly affected steel structure. M2N is the dominant precipitate, but the occurrence of σ-phase was occasionally observed especially at the interface of discontinuous precipitation and austenitic matrix. Slight increase of hardness at the grain boundaries was caused due to the precipitation of secondary phases during isothermal holding. The maximum hardness of 294 HV was measured on the sample isothermally annealed at 750 °C and holding for 10 hrs. The research provides theoretical basis for the heat affecting of steels, such as, for example, in welding.

scholarly journals OPTIMIZATION OF SYNTHESIS PROCESS OF NANOSTRUCTURED CARBIDE-CORUNDUM SILUMIN MODIFIER

2021 ◽  
Vol 1 (54) ◽  
pp. 71-79
Author(s):  
Dmitry V. ORDA ◽  
Keyword(s):  
Mathematical Model ◽  
Titanium Carbide ◽  
Response Function ◽  
Isothermal Holding ◽  
Holding Time ◽  
Synthesis Process ◽  
Synthesis Parameters ◽  
Response Equation ◽  
Main Factors ◽  
Holding Temperature

A mathematical model is developed for the process of synthesis of nanostructured modifier TiC-Al2O3 by gasphase deposition based on the system of starting materials TiO2-Al-C. To construct the response equation in the form of a polynomial of the second degree, the experiments were carried out in accordance with the model of a rotatable composite plan of the second order with three factors, including 20 experiments. The main factors considered were the isothermal holding temperature T (°C), the isothermal holding time t (s), and the proportion of the chlorinating component Q (wt.%), and as a response function — the proportion of titanium carbide q(TiC) (wt.%) in the composition of the synthesized modifier. The paper describes the results of computational and experimental modeling, from which it can be concluded that to obtain a modifier with the highest content of titanium carbide, the synthesis parameters should be as follows: T = 900–930 °C; t = 2–2.5 h; Q = 4–4.5 wt.%. The resulting TiC-Al2O3 modifier contains 34 wt.% TiC and has a nanostructured structure, with spherical and filamentous particles which diameter does not exceed 100 nm.

scholarly journals Effect of Sintering Time on the Densification, Microstructure, Weight Loss and Tensile Properties of a Powder Metallurgical Fe-Mn-Si Alloy

2017 ◽  
Author(s):  
Zhigang Xu ◽  
Michael A. Hodgson ◽  
Peng Cao
Keyword(s):  
Weight Loss ◽  
Tensile Properties ◽  
Isothermal Holding ◽  
Weight Percent ◽  
Depletion Region ◽  
Holding Time ◽  
Uniaxial Pressure ◽  
Nominal Composition ◽  
Powder Mixtures ◽  
Powder Compacts

This work investigated the isothermal holding time dependence of the densification, microstructure, weight loss and tensile properties of Fe-Mn-Si powder compacts. Elemental Fe, Mn and Si powder mixtures with a nominal composition of Fe-28Mn-3Si (in weight percent) were ball milled for 5h and subsequently pressed under a uniaxial pressure of 400 MPa. The compacted Fe-Mn-Si powder mixtures were sintered at 1200 ℃ for 0, 1, 2 and 3 h, respectively. In general, the density, weight loss and tensile properties increased with the increase of isothermal holding time. A significant increase in density, weight loss and tensile properties occurred in the compacts isothermally holding for 1 h, as compared to those with no isothermal holding. However, further extension of isothermal holding time (2 and 3 h) only played a limited role in promoting the density and tensile properties. The weight loss of the sintered compacts was mianly caused by the sublimation of Mn in Mn depletion region on the surface layer of the sintered Fe-Mn-Si compacts. The length of the Mn depletion region increased as isothermal holding time increased. A single α-Fe phase was detected on the surface of all the sintered compacts, and the locations beyond the Mn depletion region were comprised of a dual dominant γ-austenite and minor ε-martensite.

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