4083

201 دكتري

كارشناسي ارشد

مواد

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مواد

1387

[نه]، 147،[II] ص: مصور، جدول، نمودار

ص.ع.به: فارسي و انگليسي

مهدي صالحي، محمود مير واقفي

رضا مظفري نيا

16/5/87

محمود حيدر زاده سهي، فرزاد محبوبي، محمد علي گلعذار، كيوان رئيسي

مهندسي مواد

ID201 دكتري

به فارسي و انگليسي: قابل رويت در نسخه ديجيتال

AbstractLaser surface melting of Ti 6Al 4V alloy under a pure nitrogen environment was carriedout with Nd YAG pulsed laser The microstructure hardness wear and corrosionbehaviour of the nitrided samples were examined using scanning electron microscopy XRD XPS microhardness measurements fretting test and anodic polarization tests inHCl and HNO3 solution For comparison untreated samples were tested under the sameconditions The microstructures consisted mainly of a thin continuous layer of TiN followed by nearlyperpendicular dendrites and below this a mixture of small dendrites and large needles which had a random orientation The denderitic structure was the TiN phase the needlephase was TiN0 3 and the matrix was nitrogen enriched Ti An improvement incorrosion behaviour associated with the presence of a good TiN coating was observed However if the polarization potential is higher than threshold or the period of immersionis sufficiently long then the laser treated specimens will be attacked with a corrosion ratehigher than untreated Ti 6Al 4V alloy The density of TiN dendrites decreased graduallytowards the interface between the nitrided layer and the substrate The melted zone showeda range of hardness of between 400 1300 Hv this could be due to the enhanced frettingwear behavior of laser nitrided samples

مهدي صالحي، محمود مير واقفي

رضا مظفري نيا

محمود حيدر زاده سهي، فرزاد محبوبي، محمد علي گلعذار، كيوان رئيسي