Study on Homogenization Time and Cooling Rate on Microstructure and Hardness of Ni-42.5wt%Ti-3wt%Cu Alloy

2010 ◽  
Vol 297-301 ◽  
pp. 489-494 ◽  
Author(s):  
A. Etaati ◽  
Ali Shokuhfar ◽  
E. Omrani ◽  
P. Movahed ◽  
H. Bolvardi ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Hardness Test ◽  
Vacuum Arc ◽  
Melting Method ◽  
X Ray ◽  
Cu Alloy ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Homogenization Time ◽  
Cooling Media

Over the last decades, numerous investigations have been conducted on Nitinol properties. However, the effects of alloying elements on Ni-rich NiTi alloys have been considered less. In this research, different effects of homogenization time and cooling rate on the behaviors of Ni-42.5wt%Ti-3wt%Cu alloy were evaluated. The mentioned alloy was fabricated by vacuum arc melting method. Three different homogenization times (half, one and two hours) and three cooling media (water, air and furnace) were selected. The microstructure and hardness were examined by means of optical and scanning electron microscope (SEM) equipped with an energy dispersive X-ray (EDX) analysis and hardness test, respectively. According to the microscopic investigations, no significant changes were observed after half an hour. However, results indicate that increasing time of homogenization leads to finer precipitations and a uniform distribution of them. The various cooling environments result in the formation of two types of precipitation phases. It was seen that in the high cooling rate, the majority of precipitations consisted of Ti2(Ni,Cu) while by decreasing cooling rate NiTiCu precipitates appeared too, which affect the hardness.

The Effects of Homogenization Time and Cooling Environment on Microstructure and Transformation Temperatures of Ni-42.5wt%Ti-7.5wt%Cu Alloy

2010 ◽  
Vol 297-301 ◽  
pp. 344-350 ◽  
Author(s):  
E. Omrani ◽  
Ali Shokuhfar ◽  
A. Etaati ◽  
A. Dorri M. ◽  
A. Saatian
Keyword(s):  
Cooling Rate ◽  
The Other ◽  
Vacuum Arc ◽  
Electron Microscopic ◽  
Transformation Temperatures ◽  
Cu Alloy ◽  
Arc Melting ◽  
Homogenization Time ◽  
Hardness Tests ◽  
The Matrix

The present paper deals with different effects of homogenization time and cooling environment on Ni-42.5wt%Ti-7.5wt%Cu alloy. The alloy was prepared by vacuum arc melting. Afterwards, three homogenization times (half, one and two hour) and three cooling environments (water, air and furnace) at 1373 K were selected. Optical and Scanning Electron Microscopic methods, EDX, DSC and hardness tests have been used to evaluate the microstructure, transformation temperatures and hardness. Results indicate that specimens that were cooled in air are super-saturated. Also, the microstructure from furnace cooling has many disparities with the other cooling environments’ microstructure and two types of precipitates exhibit in the matrix, but in other cooling environments, only one phase can be seen. Particles of the Ti2(Ni,Cu) phase are distributed in the matrix in all of the microstructures irrespective of cooling rate. Observations show that increasing the time of homogenization results in finer precipitates and uniform distribution in the matrix. In addition, alteration of cooling rate and time of homogenization affect the martensitic transformation temperatures. On the other hand, the hardness varies slightly for different homogenization times but declines extremely with decreasing cooling rate. Moreover homogenization time and the cooling environment affect the transformation temperatures on furnace cooled samples.

Microstructure and Mechanical Properties of VTaTiMoAlx Refractory High Entropy Alloys

2017 ◽  
Vol 898 ◽  
pp. 638-642 ◽  
Author(s):  
Dong Xu Qiao ◽  
Hui Jiang ◽  
Xiao Xue Chang ◽  
Yi Ping Lu ◽  
Ting Ju Li
Keyword(s):  
Mechanical Properties ◽  
Vacuum Arc ◽  
High Entropy Alloys ◽  
X Ray Diffraction ◽  
Dendrite Structure ◽  
X Ray ◽  
High Entropy ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Microstructure And Mechanical Properties

A series of refractory high-entropy alloys VTaTiMoAlx with x=0,0.2,0.6,1.0 were designed and produced by vacuum arc melting. The effect of added Al elements on the microstructure and mechanical properties of refractory high-entropy alloys were investigated. The X-ray diffraction results showed that all the high-entropy alloys consist of simple BCC solid solution. SEM indicated that the microstructure of VTaTiMoAlx changes from equiaxial dendritic-like structure to typical dendrite structure with the addition of Al element. The composition of different regions in the alloys are obtained by energy dispersive spectroscopy and shows that Ta, Mo elements are enriched in the dendrite areas, and Al, Ti, V are enriched in inter-dendrite areas. The yield strength and compress strain reach maximum (σ0.2=1221MPa, ε=9.91%) at x=0, and decrease with the addition of Al element at room temperature. Vickers hardness of the alloys improves as the Al addition.

Microstructure, Mechanical Properties and Wear Resistance of Fe-Al Based Alloys with Various Alloying Elements

2004 ◽  
Vol 842 ◽  
Author(s):  
Han-Sol Kim ◽  
In-Dong Yeo ◽  
Tae-Yeub Ra ◽  
Won-Yong Kim
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Alloying Elements ◽  
Vacuum Arc ◽  
High Temperature Region ◽  
X Ray ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Zr Addition ◽  
Dendritic Structures

ABSTRACTWe report on microstructure, mechanical properties and wear resistance of Fe-Al based alloys with various alloying elements. The microstructures were examined using optical and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscope (EDS). Two types of alloys were prepared using vacuum arc melting; one is Fe-28Al based alloys (D03 structured) with and without alloying elements such as Mo and Zr. The other one is Fe-35Al based alloys (B2 structured) produced with same manner. For both types of alloys, equiaxed microstructures were observed by the addition of Mo, while dendritic structures were observed by the Zr addition. These microstructural features were more evinced with increasing the content of alloying elements. Concerning the mechanical properties and wear resistance, Fe-35Al based alloys with or without Mo addition superior to Fe-28Al based alloys especially in the high temperature region.

Highly Ordered Nanotube Formation on Beta Typed Ti–xTa Alloy Surface

2020 ◽  
Vol 20 (9) ◽  
pp. 5791-5795
Author(s):  
Seung-Pyo Kim ◽  
Han-Cheol Choe
Keyword(s):  
Surface Characterization ◽  
Melting Furnace ◽  
Power Source ◽  
Alloy Surface ◽  
Vacuum Arc ◽  
X Ray ◽  
Dc Power ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Martensite Structure

In this study, the highly ordered nanotube formation on beta typed Ti–xTa alloy surface was investigated. The Ti–xTa binary alloys were manufactured using a vacuum arc-melting furnace with varying Ta contents (10, 30, and 50 wt%), and then homogenized by heat treatment at 1050 °C for 1 h. The nanotube formation of Ti–xTa (x = 10–50 wt%) alloys were performed using a DC power source of 30 V in 1.0 M H3PO4 + 0.8 wt% NaF electrolyte solution for 2 hrs. The surface characterization was performed using field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The microstructure of Ti–xTa alloy showed martensite structure α′, α″-phase, and a ′-phase structure. As the Ta content increased, the needle-like structures of α′ and α′-phase gradually disappeared and only the equiaxed structure of β-phase appeared. Nanotube morphology of Ti–xTa alloy changed according to Ta content. As the Ta content increased, the size of the nanotubes decreased and the number of the smaller nanotubes increased. In the cross-sectioned nanotube layer, the gap size between the nanotubes decreased as the Ta content increased.

Alloying Element Nb Effect on Microstructure of Co-Al-W Superalloy by Vacuum Arc Melting

2012 ◽  
Vol 229-231 ◽  
pp. 63-67
Author(s):  
Yang Tao Xu ◽  
Tian Dong Xia ◽  
Wen Jun Zhao ◽  
Xiao Jun Wang
Keyword(s):  
Hardness Test ◽  
Melting Process ◽  
Xrd Analysis ◽  
Vacuum Arc ◽  
Rockwell Hardness ◽  
Pure Element ◽  
Alloying Element ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
L12 Structure

Co-Al-W supperalloy used pure element powder, according to the ratio of different atomic percentage composition to make ingredients. It is mixed by planetary ball mill, pressed into blocks after the melting shape. Vacuum arc melting process was prepared by melting, after grinding, polishing, and after a volume of 5% perchloric acid and 95% of the electrolytic etcheing solution prepared in ethanol corrosion observed after analysis of the microstructure and phase composition by XRD analysis .It can be found that Co-Al-W superalloys were mainly composed of cobalt-rich matrix of austenite precipitation of γ phase and coherent with matrix of the L12 structure of γ′-Co3(Al,W) phase. In addition, Nb have effect on grain refinement and refine grain. Rockwell hardness test and analysis, It can be found that Nb can clearly improve the Co-Al-W superalloy hardness.

Preparation and Research of AuNi Cathode Catalyst for Direct Methanol Fuel Cell

2011 ◽  
Vol 130-134 ◽  
pp. 1039-1043
Author(s):  
Shao Hui Yan ◽  
Wei Li Zhu ◽  
Shi Chao Zhang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Reduction Reaction ◽  
Vacuum Arc ◽  
Methanol Tolerance ◽  
X Ray ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Electrocatalytic Oxygen Reduction ◽  
Direct Methanol ◽  
Electron Reduction

AuNi alloy was synthesized by vacuum arc melting in high-purity argon atmosphere. The AuNi alloy was characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The results of EDS indicated that Au and Ni atoms were well-distributed in the alloy. Moreover, the results of XPS exhibited an electronic transfer from Ni to Au in AuNi phase. The Electrocatalytic oxygen reduction reaction (ORR) activity and the methanol tolerance of the AuNi alloy were respectively investigated using the RDE method and the electrochemical cyclic voltammetry. The results suggested that O2was directly oxidized to H2O on the AuNi catalyst via an approximate four-electron reduction pathway, and that the AuNi catalyst had a high electrocatalytic activity for the ORR and an acceptable methanol tolerance, simultaneously.

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