Effect of Casting Condition on Density and Hardness Gradients of Al-Al2Cu Alloy FGM Fabricated by Centrifugal In Situ Method

2009 ◽  
Vol 631-632 ◽  
pp. 449-454 ◽  
Author(s):  
Kenichi Tabushi ◽  
Hisashi Sato ◽  
Yoshimi Watanabe
Keyword(s):  
Density Gradient ◽  
Master Alloy ◽  
Early Stage ◽  
Functionally Graded ◽  
Processing Temperature ◽  
Casting Condition ◽  
Cu Alloy ◽  
In Situ Method ◽  
Master Alloys

Functionally graded material (FGM) is a combined material that has a component gradient from one material at one surface to another material at the opposite surface. 　As one of the fabrication processes of FGM, centrifugal in-situ method has been proposed. Centrifugal in-situ method is a casting that centrifugal force is applied during solidification to both the primary crystal and the matrix. In a previous study, the density and hardness gradients of Al-3mass%Cu FGM ring fabricated by centrifugal in-situ method have been investigated. According to the study, Cu concentration within the FGM ring monolithically increases towards the ring's inner position, and its density also increases toward inner region. This is because the density of the primary -Al crystal is larger than that of the molten Al-Cu alloy in the early stage of solidification. Based on this solidification process, it is considered that the casting condition and the initial Cu concentration of Al-Cu master alloy affect on the density and hardness gradients in the Al-Cu FGM ring. In this study, effects of the casting condition on the density and hardness gradients of Al-Al2Cu FGM rings fabricated by the centrifugal in-situ method were investigated. It was found that density gradient of the Al-Al2Cu FGM rings increases with increasing Cu concentration of Al-Cu master alloys. Also, processing temperature for Al-Cu master alloy can control density gradient of Al-Al2Cu FGM rings. These phenomena were explained by variation of the densities of primary -Al and the molten Al matrix during the solidification.

scholarly journals Investigation of Microstructure of Al-5Ti-0.62C System and Synthesis Mechanism of TiC

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 310 ◽  
Author(s):  
Wanwu Ding ◽  
Taili Chen ◽  
Xiaoyan Zhao ◽  
Yan Cheng ◽  
Xiaoxiong Liu ◽  
...  
Keyword(s):  
Master Alloy ◽  
Pure Aluminum ◽  
Preparation Process ◽  
Synthesis Mechanism ◽  
Microstructure Transformation ◽  
Master Alloys ◽  
Refining Performance ◽  
Commercial Pure Aluminum ◽  
Positive Effect

Al-Ti-C master alloys have been widely investigated by various researchers. However, their refining effectiveness is still severely compromised by the preparation process. In this work, the aluminum melt in-situ reaction was carried out to synthesize the Al-5Ti-0.62C, and its refining performance was estimated. The thermodynamics calculation and differential scanning calorimeter experiment were used to investigate the synthesis mechanism of TiC. Quenching experiment was conducted to explore phase and microstructure transformation of the Al-5Ti-0.62C system. The results show that the main phases of Al-5Ti-0.62C master alloys are α-Al, Al3Ti, and TiC and it has a positive effect on commercial pure aluminum refining. Commercial pure aluminum is completely refined into the fine equiaxed structure by adding 0.3% Al-5Ti-0.62C master alloy. TiC particles mainly distribute in the grain interior and grain boundaries. The excess Ti came from the dissolution of Al3Ti spreading around TiC and finally forming the Ti-rich zone to promote the nucleation of α-Al. The experiments certified that TiC was formed by the reaction between solid C and excess Ti atoms. The main reactions in the Al-5Ti-0.62C system were that solid Al is transferred into liquid Al, and then liquid Al reacted with solid Ti to form the Al3Ti. At last, the release of a lot of heat promotes the formation of TiC which formed by the Ti atoms and solid C.

Effects of the Processing Temperature of Centrifugal Casting on the Mechanical Properties of Al-Al3Ti FGMs

2009 ◽  
Vol 631-632 ◽  
pp. 373-378 ◽  
Author(s):  
Shimaa El Hadad ◽  
Hisashi Sato ◽  
P.D. Sequeira ◽  
Yoshimi Watanabe ◽  
Yoshihito Oya-Seimiya
Keyword(s):  
Mechanical Properties ◽  
Solid Particle ◽  
Centrifugal Casting ◽  
Particle Method ◽  
Second Phase ◽  
Processing Temperature ◽  
Wear Property ◽  
Initial State ◽  
In Situ Method

Formation of the compositional gradient in FGMs fabricated by centrifugal casting method depends mainly on the processing temperature and the applied centrifugal force. According to the initial state of the dispersed second phase at the processing temperature, CCM-FGMs can be classified into two categories. One is the FGM fabricated by centrifugal solid-particle method, and the other one is the FGM made by centrifugal in-situ method. In previous study, it has been reported that microstructure of Al-Al3Ti FGMs by centrifugal in-situ method was different from that by centrifugal solid-particle method. However, difference of mechanical property due to processing method is still unclear. In this study, mechanical properties, such as hardness and wear property of Al-Al3Ti FGMs fabricated by centrifugal solid-particle method and in-situ method were evaluated.

scholarly journals Action of Chlorhexidine Digluconate against Yeast and Filamentous Forms in an Early-Stage Candida albicans Biofilm

2002 ◽  
Vol 46 (11) ◽  
pp. 3522-3531 ◽  
Author(s):  
Peter A. Suci ◽  
Bonnie J. Tyler
Keyword(s):  
Candida Albicans ◽  
Biofilm Formation ◽  
Early Stage ◽  
Cell System ◽  
Accurate Estimation ◽  
Interfacial Region ◽  
In Situ Method ◽  
The Difference ◽  
Kinetics Of

ABSTRACT An in situ method for sensitive detection of differences in the action of chlorhexidine against subpopulations of cells in Candida albicans biofilms is described. Detection relies on monitoring the kinetics of propidium iodide (PI) penetration into the cytoplasm of individual cells during dosing with chlorhexidine. Accurate estimation of the time for delivery of the dosing concentration to the substratum was facilitated by using a flow cell system for which transport to the interfacial region was previously characterized. A model was developed to quantify rates of PI penetration based on the shape of the kinetic data curves. Yeast were seeded onto the substratum, and biofilm formation was monitored microscopically for 3 h. During this period a portion of the yeast germinated, producing filamentous forms (both hyphae and pseudohyphae). When the population was subdivided on the basis of cell morphology, rates of PI penetration into filamentous forms appeared to be substantially higher than for yeast forms. Based on the model, rates of penetration were assigned to individual cells. These data indicated that the difference in rates between the two subpopulations was statistically significant (unpaired t test, P < 0.0001). A histogram of rates and analysis of variance indicated that rates were approximately equally distributed among different filamentous forms and between apical and subapical segments of filamentous forms.

Formation of Compositional Gradient during Fabrication of FGMs by a Centrifugal In Situ Method

2005 ◽  
Vol 492-493 ◽  
pp. 693-698 ◽  
Author(s):  
Yoshimi Watanabe ◽  
Shin Oike ◽  
Ick Soo Kim
Keyword(s):  
Chemical Composition ◽  
Eutectic Alloy ◽  
Density Difference ◽  
Primary Crystal ◽  
Compositional Gradient ◽  
Cu Alloy ◽  
In Situ Method ◽  
The Matrix ◽  
Primary Crystals

The purpose of the present work is to study the formation of the compositional gradient during the fabrication of FGMs by a centrifugal in-situ method. Al-Al2Cu FGMs were fabricated by the centrifugal in-situ method using eutectic Al-33mass%Cu alloy, and the microstructures of fabricated FGMs were studied. It was found that the Al-Al2Cu FGMs could be fabricated by the centrifugal in-situ method from eutectic alloy. Based on the experimental results, the formation mechanism of the compositional gradient during the fabrication of FGM by the centrifugal in-situ method in the A-B alloy could be summarized as follows; 1) Partial separation of A and B elements in the liquid state occurs due to the density difference. 2) A compositional gradient is formed before the crystallization of the primary crystal. 3) The primary crystals in the matrix appear to depend on local chemical composition. 4) The primary crystals migrate according to density difference, and a further compositional gradient is formed.

scholarly journals Preparation of Novel Al-Er Master Alloys in Chloride-Fluoride Melt

2018 ◽  
Vol 918 ◽  
pp. 21-27 ◽  
Author(s):  
Yaroslav Igorevich Kosov ◽  
Vladimir Yuryevich Bazhin
Keyword(s):  
Master Alloy ◽  
Eutectic Reaction ◽  
The Novel ◽  
X Ray Diffraction ◽  
Metallothermic Reduction ◽  
Master Alloys ◽  
Backscattered Electron ◽  
The Cost ◽  
Electron Imaging

A novel Al-Er master alloy has been prepared through in situ metallothermic reactions of NaErF4 and aluminium melts. The compound NaErF4 is formed as a result of the interaction of NaF and ErF3 in the melt medium KCl. The metallothermic reactions produce erbium, which through low solubility in molten aluminium and forms intermetallic compound Al3Er. The microstructures of the Al-Er master alloy with different contents of the alloying metal has been investigated. The results showed that the Al-Er master alloy mainly consisted of phases of α-Al and Al3Er, that confirmed by the results of X-ray diffraction. Backscattered electron imaging of the Al-Er master alloy under a scanning electron microscope (SEM) revealed the presence of phase Al3Er, which crystallized in the eutectic composition [Al+Al3Er]. The observed microstructure is explained according to the eutectic reaction in an Al-Er phase diagram. The preparation of Al-Er master alloy by the metallothermic reduction method will allow to reduce energy consumption for master alloy production and to reduce the cost of aluminium alloys alloyed with Er through the novel master alloy.

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