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Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying

In this study, nanocomposite of (Mo,W)Si2–WSi2 was synthesized via mechanical alloying (MA) and heat treatment. The phase transformation of the powders after various milling durations and annealing was investigated by X-ray diffraction (XRD) and differential thermal analysis (DTA). Microstructural e...

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Main Authors:	Zamani, Shahrouz, Bakhsheshi-Rad, Hamid Reza, Abdul Kadir, Mohammed Rafiq, MohammadShafiee, Mohammad Reza
Format:	Article
Published:	Elsevier Ltd. 2012
Subjects:	TA Engineering (General). Civil engineering (General)
Online Access:	http://eprints.utm.my/id/eprint/47573/ http://dx.doi.org/10.1016/j.jallcom.2012.06.072
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spelling	my.utm.475732020-02-29T13:19:10Z http://eprints.utm.my/id/eprint/47573/ Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying Zamani, Shahrouz Bakhsheshi-Rad, Hamid Reza Abdul Kadir, Mohammed Rafiq MohammadShafiee, Mohammad Reza TA Engineering (General). Civil engineering (General) In this study, nanocomposite of (Mo,W)Si2–WSi2 was synthesized via mechanical alloying (MA) and heat treatment. The phase transformation of the powders after various milling durations and annealing was investigated by X-ray diffraction (XRD) and differential thermal analysis (DTA). Microstructural evolutions were characterized by scanning electron microscopy and transmission electron microscopy (TEM). Increasing the milling time to 80 h caused the formation of (Mo, W, Si) solid solution, t-(Mo,W)Si2, h-WSi2 phase, and a trace amount of unreacted raw material. However the post-annealing at 1000 °C caused the complete formation of (Mo,W)Si2–WSi2 nanocomposite. The values of the grain growth exponent of t-(Mo,W)Si2 phase for the powders milled for 40 and 80 h were 0.3 and 0.8, respectively, at 1000 °C. The grain growth activation energy of t-(Mo,W)Si2 phase for the 80 h milled powders (97.19 KJ/mol) was lower than that for the 40 h sample (120.83 KJ/mol). The crystallite size of t-(Mo,W)Si2 decreased to 32 nm (40 h) and 24 nm (80 h) with increasing milling time. However, the crystallite size of the milled samples increased to 60 and 87 nm after annealing at 1000 °C for 90 min. The DTA results of the as-milled specimens showed two exothermic peaks at around 600 and 900 °C relating to the formation of t-(Mo,W)Si2 and h-WSi2, respectively. The formation activation energy of t-(Mo,W)Si2 was higher (144.58 KJ/mol) for the 80 h milled sample compared to the 40 h milled sample (131.61 KJ/mol). The microhardness of (Mo,W)Si2–WSi2 nanocomposite increased with increasing milling time to 1020 Hv but decreased with escalating annealing temperature to 726 Hv. Elsevier Ltd. 2012 Article PeerReviewed Zamani, Shahrouz and Bakhsheshi-Rad, Hamid Reza and Abdul Kadir, Mohammed Rafiq and MohammadShafiee, Mohammad Reza (2012) Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying. Journal Of Alloys And Compounds, 540 . pp. 248-259. ISSN 0925-8388 http://dx.doi.org/10.1016/j.jallcom.2012.06.072 DOI:10.1016/j.jallcom.2012.06.072
institution	Universiti Teknologi Malaysia
building	UTM Library
collection	Institutional Repository
continent	Asia
country	Malaysia
content_provider	Universiti Teknologi Malaysia
content_source	UTM Institutional Repository
url_provider	http://eprints.utm.my/
topic	TA Engineering (General). Civil engineering (General)
spellingShingle	TA Engineering (General). Civil engineering (General) Zamani, Shahrouz Bakhsheshi-Rad, Hamid Reza Abdul Kadir, Mohammed Rafiq MohammadShafiee, Mohammad Reza Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying
description	In this study, nanocomposite of (Mo,W)Si2–WSi2 was synthesized via mechanical alloying (MA) and heat treatment. The phase transformation of the powders after various milling durations and annealing was investigated by X-ray diffraction (XRD) and differential thermal analysis (DTA). Microstructural evolutions were characterized by scanning electron microscopy and transmission electron microscopy (TEM). Increasing the milling time to 80 h caused the formation of (Mo, W, Si) solid solution, t-(Mo,W)Si2, h-WSi2 phase, and a trace amount of unreacted raw material. However the post-annealing at 1000 °C caused the complete formation of (Mo,W)Si2–WSi2 nanocomposite. The values of the grain growth exponent of t-(Mo,W)Si2 phase for the powders milled for 40 and 80 h were 0.3 and 0.8, respectively, at 1000 °C. The grain growth activation energy of t-(Mo,W)Si2 phase for the 80 h milled powders (97.19 KJ/mol) was lower than that for the 40 h sample (120.83 KJ/mol). The crystallite size of t-(Mo,W)Si2 decreased to 32 nm (40 h) and 24 nm (80 h) with increasing milling time. However, the crystallite size of the milled samples increased to 60 and 87 nm after annealing at 1000 °C for 90 min. The DTA results of the as-milled specimens showed two exothermic peaks at around 600 and 900 °C relating to the formation of t-(Mo,W)Si2 and h-WSi2, respectively. The formation activation energy of t-(Mo,W)Si2 was higher (144.58 KJ/mol) for the 80 h milled sample compared to the 40 h milled sample (131.61 KJ/mol). The microhardness of (Mo,W)Si2–WSi2 nanocomposite increased with increasing milling time to 1020 Hv but decreased with escalating annealing temperature to 726 Hv.
format	Article
author	Zamani, Shahrouz Bakhsheshi-Rad, Hamid Reza Abdul Kadir, Mohammed Rafiq MohammadShafiee, Mohammad Reza
author_facet	Zamani, Shahrouz Bakhsheshi-Rad, Hamid Reza Abdul Kadir, Mohammed Rafiq MohammadShafiee, Mohammad Reza
author_sort	Zamani, Shahrouz
title	Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying
title_short	Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying
title_full	Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying
title_fullStr	Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying
title_full_unstemmed	Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying
title_sort	synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying
publisher	Elsevier Ltd.
publishDate	2012
url	http://eprints.utm.my/id/eprint/47573/ http://dx.doi.org/10.1016/j.jallcom.2012.06.072
_version_	1662754252130353152
score	13.211869

Synthesis and kinetic study of (mo,w)si 2-wsi 2 nanocomposite by mechanical alloying

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