تاثير انرژي فرايند آسياب كاري بر مكانيزم تشكيل تركيبات بين فلزي نانو ساختار Ni-Ti-Al و مشخصه يابي پوشش هاي پاشش پلاسمايي حاصل از آن

چكيده انگليسي :

The Effect of Energy System Impact in Mechanical Alloying MA on the Formation Mechanism of Nanostructure Intermetallic Ni Ti Al Alloys and Characterization of Its Plasma Spray Coatings Hessam Rezvani Sichani h rezvanisichani@ma iut ac ir Date of Submission 19 5 2012 Department of Material Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Mehdi Salehi Surfacesalehi@hotmail com Hosein Edris h edris@cc iut ac ir Abstract Ni Ti Al Intermetallic Compounds have been extensively studied in the recent years due to their promising engineering applications specifically in the field of high temperature due to high corrosion resistance and excellent high temperature strength There are different methods to produce intermetallic compounds The most widely used of these methods include powder metallurgy mechanical alloying and SHS Despite some limitations mechanical alloying MA is one of the best methods for making and production of intermetallic compounds because of low production cost and its simple process This study primarily aimed at investigating compounds formed during MA of Ni 25Ti 25Al system As such the prepared powder mixture was milled In order to avoid unwanted reactions mechanical alloying was carried out under argon atmosphere Moreover since the final product and its formation speed through MA depends on ball mill energy parameter this study also examined the effect of ball mill energy on the formation of compounds This being so alloying was conducted in planetary ball mill and attritor Microstructure investigations were made by X ray diffraction XRD Scanning Electron Microscope SEM thermal analysis and microhardness surveys The results revealed that MA of powder mixture led to the formation of Ni3 Ti Al Nanostructured compounds with irregular L12 structure It was observed that during MA with the formation of layer structure and diffusion of Ti and Al atoms into Ni lattice the aforementioned solid solution was created and after continuing the MA it changed into Ni3 Ti Al Heat treatment of product under different conditions leads to decomposition of a part of the Ni3 Ti Al phase to other intermetallic phases In the end after heat treatment an alloy of multiple phases was formed Heat treatment leads to regulation of Ni3 Ti Al network and appearance of its superlattice peaks In order to increase the efficiency of the parts and industrial tools it is necessary to conduct appropriate surface treatment or coating on the parts hence surface engineering is of great importance nowadays Intermetallic compounds coatings on ferrous and nonferrous substrates have received considerable attention due to resistance to wear and perfect oxidation and relatively lower friction coefficient Moreover this study examined the evolution of Ni Ti Al intermetallic coating microstructure conducted in APS methods on carbon steel substrate In order to investigate the effect of thermal spray current on coating 4 different current Amp were used Appropriate powder for thermal spray was produced by ball mill of powder for 2 hours in attritor ball mill In order to characterization of coating various tests were performed on them The results showed that after the spraying the Ni2TiAl NiTiAl Ni solid solution and some TiO2 were formed In the coating an increase in the plasma temperature to a certain degree can lead to a reduction in intermetallic compounds an increase in porosity and a decrease in coating hardness The produced coating with the lowest current intensity has the highest adhesion in substrate and the lowest toughness According to the results the produced coating with the lowest current intensity has optimized conditions Keywords Ni Ti Al intermetallic compounds Mechanical alloying Nanostructure Materials APS

رضواني سيچاني، حسام

تاثير انرژي فرايند آسياب كاري بر مكانيزم تشكيل تركيبات بين فلزي نانو ساختار Ni-Ti-Al و مشخصه يابي پوشش هاي پاشش پلاسمايي حاصل از آن

آلياژ سازي مكانيكي , پاشش پلاسمايي اتمسفري