Time filter

Source Type

Carcea I.,Technical University Gheorghe Asachi | Mareci D.,Technical University Gheorghe Asachi | Roman C.,Technical University Gheorghe Asachi | Soare V.,National Research and Development Institute for Nonferrous and Rare Metals | Chelariu R.,Technical University Gheorghe Asachi
Metalurgia International | Year: 2011

The present paper presents the studies concerning the topographies and chemical compositions of Zn-Ni-P layers electrodeposited on carbon steel substrates in chloride and sulphate solutions. The analysis of the topography and of the surface chemical composition for the samples covered with thin films of Zn-Ni-P was conducted with the help of SEM analysis coupled with EDX. These preliminary experiments of electrochemical deposition of the layers of Zn-Ni-P on carbon steel substrate have shown the possibility of obtaining some layers with different topographies and surface chemical compositions, depending on the employed experimental conditions. The layers are much more obvious when using chloride based electrolytes when compared with sulphate based electrolytes.


Florea I.,Technical University Gheorghe Asachi | Florea R.M.,Technical University Gheorghe Asachi | Baltatescu O.,Technical University Gheorghe Asachi | Soare V.,National Research and Development Institute for nonferrous and Rare Metals | And 2 more authors.
Advanced Materials Research | Year: 2014

In 1995, Yeh suggested the formation of an alloy made up of at least five metallic elements which have large mixing entropy solutions with many elements forming solide alloys. This alloy appeared because traditional alloys are characteised by high fragility and are difficult to process. High entropy alloys are alloys which have approximately equal concentrations, formed by a group of 5 to 11 elements majority in composition, mole fraction of each major metallic element in the alloy is between 5% and 30%. During the research it has been proved that this alloy has a high hardness and it is also corrosion proof and also resistance and good thermal stability.It should be mentioned that High Entropy Alloys are characterized as alloys consisting of roughly equal concentrations of at least five metallic elements and are claimed to favor close-packed, disordered structures due to high configurational entropy. This opens the door to a large number of rich chemistries which would otherwise contain unacceptable volume fractions of intermetallic compounds to be useful in structural applications. That way in this paper will carry out research to one specific high entropy alloy, we analyze the physical, chemical, electrical, magnetic, corrosion resistance of these materials, heat treatments corresponding and plastic deformation. This paper is divided into several chapters which will present application domains, and also a number of conclusions. © (2014) Trans Tech Publications, Switzerland.


Florea I.,Technical University Gheorghe Asachi | Buluc G.,Technical University Gheorghe Asachi | Florea R.M.,Technical University Gheorghe Asachi | Soare V.,National Research and Development Institute for Nonferrous and Rare Metals | Carcea I.,Technical University Gheorghe Asachi
IOP Conference Series: Materials Science and Engineering | Year: 2015

High-entropy alloy is a new alloy which is different from traditional alloys. The high entropy alloys were started in Tsing Hua University of Taiwan since 1995 by Yeh et al. Consisting of a variety of elements, each element occupying a similar compared with other alloy elements to form a high entropy. We could define high entropy alloys as having approximately equal concentrations, made up of a group of 5 to 11 major elements. In general, the content of each element is not more than 35% by weight of the alloy. During the investigation it turned out that this alloy has a high hardness and is also corrosion proof and also strength and good thermal stability. In the experimental area, scientists used different tools, including traditional casting, mechanical alloying, sputtering, splat-quenching to obtain the high entropy alloys with different alloying elements and then to investigate the corresponding microstructures and mechanical, chemical, thermal, and electronic performances. The present study is aimed to investigate the corrosion resistance in a different medium acid and try to put in evidence the mechanical properties. Forasmuch of the wide composition range and the enormous number of alloy systems in high entropy alloys, the mechanical properties of high entropy alloys can vary significantly. In terms of hardness, the most critical factors are: hardness/strength of each composing phase in the alloy, distribution of the composing phases. The corrosion resistance of an high entropy alloy was made in acid liquid such as 10%HNO3-3%HF, 10%H2SO4, 5%HCl and then was investigated, respectively with weight loss experiment. Weight loss test was carried out by put the samples into the acid solution for corrosion. The solution was maintained at a constant room temperature. The liquid formulations used for tests were 3% hydrofluoric acid with 10% nitric acid, 10% sulphuric acid, 5% hydrochloric acid. Weight loss of the samples was measured by electronic scale..

Loading National Research and Development Institute for Nonferrous and Rare Metals collaborators
Loading National Research and Development Institute for Nonferrous and Rare Metals collaborators