scholarly journals Microstructural Evolution of Dy2O3-TiO2 Powder Mixtures during Ball Milling and Post-Milled Annealing

Materials ◽  
2016 ◽  
Vol 10 (1) ◽  
pp. 19 ◽  
Author(s):  
Jinhua Huang ◽  
Guang Ran ◽  
Jianxin Lin ◽  
Qiang Shen ◽  
Penghui Lei ◽  
...  
Author(s):  
Yong Luo ◽  
Guang Ran ◽  
Nanjun Chen ◽  
Qiang Shen ◽  
Yaoli Zhang

The microstructural evolution, thermodynamics and kinetics of Mo-21%Tm2O3 (mass fraction, %) powder mixtures during ball milling were investigated using X-ray diffraction and transmission electron microscopy. Ball milling induced Tm2O3 to be decomposed and then dissolved into Mo crystal. The supersaturated nanocrystalline solid solution of Mo (Tm, O) was obtained after 96 h of ball milling. The elements of Mo, Tm and O were distributed uniformly in the ball-milled particles. Based on the semi-experimental theory of Miedema, a thermodynamic model was developed to calculate the driving force of phase evolution. There was no chemical driving force to form a crystal solid solution of Tm atoms in Mo crystal or an amorphous phase because the Gibbs free energy for both processes was higher than zero. For Mo-21%Tm2O3, it was mechanical work, not negative heat of mixing, that provided the driving force to form supersaturated nanocrystalline Mo (Tm, O) solid solution.


Materials ◽  
2016 ◽  
Vol 9 (10) ◽  
pp. 834 ◽  
Author(s):  
Yong Luo ◽  
Guang Ran ◽  
Nanjun Chen ◽  
Qiang Shen ◽  
Yaoli Zhang

1998 ◽  
Vol 33 (10) ◽  
pp. 2519-2527 ◽  
Author(s):  
F Cardellini ◽  
V Contini ◽  
R Gupta ◽  
G Mazzone ◽  
A Montone ◽  
...  

2004 ◽  
Vol 379 (1-2) ◽  
pp. 216-221 ◽  
Author(s):  
Nada Stubičar ◽  
Vladimir Bermanec ◽  
Mirko Stubičar ◽  
Darko Popović ◽  
Wolfgang A. Kaysser

2016 ◽  
Vol 869 ◽  
pp. 58-63
Author(s):  
Luiz Otávio Vicentin Maruya ◽  
Bruna Rage Baldone Lara ◽  
Belmira Benedita de Lima ◽  
Vanessa Motta Chad ◽  
Gilberto Carvalho Coelho ◽  
...  

This study reports on effect of boron and carbon addition on the phase transformations during ball milling and subsequent sintering of Si3N4+B and Si3N4+C powder mixtures. Ball milling at room temperature was conducted using stainless steel vials (225 mL) and balls (19mm diameter), 300 rpm and a bal-to-powder weight ratio of 10:1. The as-milled powders were uniaxially compacted in order to obtain cylinder samples with 10 mm diameter, which were subsequently sintered under nitrogen atmosphere at 1500°C for 1h. Characterization of the as-milled powders and sintered samples was performed by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. Only peaks of Si3N4 were identified in X-ray diffractograms of as-milled Si3N4+B and Si3N4+C powders, suggesting that metastable structures were found during milling. After sintering at 1500°C for 1h, the Si3N4+BN and Si3N4+SiC ceramic composites were formed from the mechanically alloyed Si3N4+B and Si3N4+C powders.


2010 ◽  
Vol 660-661 ◽  
pp. 329-334 ◽  
Author(s):  
Railson Bolsoni Falcão ◽  
Edgar Djalma Campos Carneiro Dammann ◽  
Cláudio José da Rocha ◽  
Ricardo Mendes Leal Neto

This work reports the efforts to obtain TiFe intermetallic compound by high-energy ball milling of Ti and Fe powder mixtures. This process route has been used to provide a better hydrogen intake in this compound. Milling was carried out in a SPEX mill at different times. Strong adherence of material at the vial walls was seen to be the main problem at milling times higher than 1 hour. Attempts to solve this problem were accomplished by adding different process control agents, like ethanol, stearic acid, low density polyethylene, benzene and cyclohexane at variable quantities and keeping constant other milling parameters like ball to powder ration and balls size. Better results were attained with benzene and cyclohexane, but with partial formation of TiFe compound even after a heat treatment (annealing) of the milled samples.


2012 ◽  
Vol 05 ◽  
pp. 638-645 ◽  
Author(s):  
S. ALAMOLHODA ◽  
S. HESHMATI-MANESH ◽  
A. ATAIE ◽  
A. BADIEI

In this study effect of adding various process control agents (PCAs) to powder mixtures of Al and TiO 2 which are mechanically activated so as to form TiAl - Al 2 O 3 nano-composite have been investigated. Phase constitutions and morphology of the milled powders were evaluated by XRD and SEM techniques, respectively. The mean crystallite sizes of the milled powders were calculated by Cauchy-Gaussian method. Thermal behavior of the milled powders was also studied by DTA to investigate formation of the final phases. The results showed that the mean crystallite size of the milled powders in the presence of PCAs was smaller than that of the sample milled without PCA addition. DTA traces showed that addition of PCAs retards the reduction of TiO 2 by Al . In samples milled in presence of PCA, the reductive reaction generally took place after melting of Al particles whereas the sample milled without PCA addition showed an opposite behavior. Also, in comparison with the sample milled with no PCA addition, in other samples the reductive reaction took place at relatively lower temperatures.


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