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Volume 6 Research & Reviews: Journal of Material Sciences CrystalloPolySci 2018
November 19-20, 2018
4th International Conference on
Crystallography & Novel Materials
&
9th International Conference on
Biopolymers & Polymer Sciences
November 19-20, 2018 Bucharest, Romania
Zafar Iqbal, Res. Rev. J Mat. Sci. 2018, Volume 6
DOI: 10.4172/2321-6212-C9-038
Microstructural evolution of nano-crystalline tungsten-25% rhenium-hafnium carbide composite
synthesized by spark plasma sintering technique for FSW tool application
Zafar Iqbal
Pakistan Institute of Engineering and Applied Sciences (PIEAS), Pakistan
Development of nano-crystalline tungsten-25% rhenium alloy reinforced with hafnium carbide is a challenging task as
these alloys are difficult to synthesize by conventional methods. The problem of these difficult to alloy elements can be
addressed by using a unique combination of mechanical alloying and Spark Plasma Sintering (SPS) techniques via powder
metallurgy route. Rhenium was added to lower ductile-to-brittle transition temperature and to increase recrystallization
temperature of tungsten. SPS is rapid consolidating technique which prevents grain growth. These tool materials can withstand
high temperatures and harsh conditions in joining application such as Friction Stir Welding (FSW) of steel and titanium
alloys. FSW is a green process which does not emit fume and toxic fumes during the process. Sintering was carried between
1500-1800 °C. Mechanically alloyed and SPS alloy and composite were characterized by optical microscopy, Field Emission
Scanning Electron Microscopy (FESEM) and X-ray Diffraction. Microstructural investigations of consolidated specimens were
initially carried out by conventional etching and metallography techniques. Optical micrographs showed no visible signs of
grain boundary etching. SPS samples were further electrochemically etched in one molar concentrated solution of NaOH.
The positive terminal of the low voltage direct current power supply was connected to the sample. The negative terminal was
connected to a steel plate acting as cathode. Both electrodes were placed in the tank face to face with a gap of 6 to 10 centimeters
between them. The voltage was kept constant as 5 volt during the etching process. Samples were etched for short time interval
from 1 to 5 seconds and microstructural analysis was conducted after each etching step. The results of the FESEM images
confirm microstructural revelation of these difficult to etch alloy and composites.
Biography
Zafar Iqbal has completed his PhD from King Fahd University of Petroleum and Minerals KFUPM, KSA. Currently, he is the Assistant Professor at Pakistan Institute
of Engineering and Applied Sciences (PIEAS), Islamabad. He has published more than 6 papers in reputed journals.