ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
A comparative study on the microstructure-mechanical property relationships in themolybdenum and niobium silicide based composites has been carried out with emphasis on the roleof the ductile and brittle phase constituents at ambient and elevated temperatures. The MoSi2,MoSi2-20 vol.% SiC and -Mo-Mo3Si-Mo5SiB2 composites have been prepared by powdermetallurgy processing. Furthermore, the niobium silicide based composites, having a eutectic of Nbsolid solution (Nbss) and (Nb,Mo)5Si3, and either Nbss or (Nb,Mo)5Si3 as the primary phase in thehypoeutectic or hypereutectic compositions, respectively, have been processed by arc melting. Theincrease in fracture toughness with respect to that of MoSi2 is modest in the MoSi2-SiC composites,and more significant in the multiphase Mo-Mo3Si-Mo5SiB2 and Nbss-(Nb,Mo)5Si3 based in-situcomposites with ductile reinforcements. The ductile phase, either Mo or Nbss aids in tougheningchiefly through crack arrest and bridging, and undergoes plastic yielding under constraint duringdeformation, leading to a higher energy of fracture. In the MoSi2 and MoSi2-SiC composites, thematrix grain size has a significant role in high temperature strength retention and strain hardeningbehaviour. In the ductile phase reinforced composites, the hard silicide-based intermetallic phasescontribute to elevated temperature strength, while the constrained plastic deformation of the -Moor Nbss is responsible for much higher rate of strain hardening than in the MoSi2 and MoSi2-SiCcomposites
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/57/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.395.179.pdf
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