Corrosion behavior of Zr-based metallic glass coating on type 304L stainless steel by pulsed laser deposition method S. Ningshen, U. Kamachi Mudali ⁎, R. Krishnan, Baldev Raj Indira Gandhi Centre for Atomic Research, Kalpakkam-603 102, India abstract article info Article history: Received 8 September 2010 Accepted in revised form 14 February 2011 Available online 19 February 2011 Keywords: Corrosion Glassy metallic alloy Nitric acid PLD AFM The surface morphology and corrosion behavior of Zr-based amorphous metallic glass (MG) of Zr 59 Ti 3 Cu 20- Al 10 Ni 8 alloy and MG coated type 304L stainless steel in different nitric acid media of 1 M, 6 M and 11.5 M HNO 3 is reported. Zirconium based MG of Zr 59 Ti 3 Cu 20 Al 10 Ni 8 alloy was successfully deposited on type 304L stainless steel using pulsed laser deposition technique. The SEM morphology revealed a scattered particles of “Donut” shaped features distributed in the amorphous matrix. The atomic force microscope measurement indicated the formation of dense metallic deposited layer of agglomerate of granular clusters with negligible pores or micro-crack in metallic glass coated sample. The results of the potentiodynamic polarization shows that the amorphous MG coated type 304L stainless steel exhibited marginally lower corrosion resistance than MG alloy which is attributed to the presence of corrosion-induced defects in the coated layer. This work reports suitability of using pulsed laser deposition for the preparation of thin film amorphous metallic coating to achieve improved corrosion resistance in nitric acid medium. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Amorphous MG alloys have attracted great interest in recent years due to their many useful properties with great potential for several industrial and as well as for bio-medical applications [1,2]. Compared to crystalline counterparts, amorphous MG alloys possess unique properties of high strength, high elastic limit, relatively low Young's modulus, good wear resistance, magnetic properties, fatigue endur- ance, and corrosion resistance [1–3]. Among bulk glass-forming system, Zr-based multi-component alloys possess great potential for application in nitric acid environment [4–6], in comparison with conventional materials such as AISI 304L stainless steel (SS) which undergoes severe general and intergranular corrosion (IGC) attacks in concentrated nitric acid media [7]. Zirconium based alloys are important materials in nuclear industry due to low neutron absorption coefficient and high corrosion resistance [7,8]. However despite possessing many interesting features, MG alloys are not commonly used in engineering or structural applications because of its low tensile ductility, toughness and restricted thickness [1,3]. Therefore coating of amorphous MG is more attractive than the use of bulk MG alloys for practical applications in corrosive environments. Amorphous MG alloys are typically produced by rapid quenching from the liquid or vapor phase, which hinders the crystallization kinetics [9]. Several preparation techniques used for producing such amorphous MG alloys include the followings; mechanical alloying (solid-state reaction), melt-spinning (rapid cooling technique), splat-cooling or gas- atomization, solidification technique (water-quenching, copper-mold casting, high-pressure die casting, arc melting, unidirectional melting, suction casting and squeeze casting) [2,3,10,11], hot pressing and warm extrusion of atomized amorphous powders [3,10]. Similarly, variety of metallic glasses in the form of thin films, or powders can be obtained by interdiffusion and interfacial reaction at temperatures well below the glass transition temperatures [12]. In the recent past decades several attempts were made to obtain corrosion resistant amorphous alloys and coatings on crystalline substrate [13–17]. Among these, pulsed laser deposition (PLD) technique is a promising and useful technique that can be used to produce amorphous, hard, wear and corrosion resistant surfaces on the steel substrates [13]. A great advantage of PLD is the retention of the stoichiometry of virtually any target material during the deposition. PLD is one of the few deposition techniques that can deposit coating at room temperature (to retain the glassy structure) with moderate energy (ranging from 10 to 100 eV of the ablation species) that is sufficient to densify the structure of the coating and provide enhanced adhesion [13]. Bulk metallic powder coated on glass by laser processing was recently reported [15]. Basu et al. [16] coated Fe 48 Cr 15 Mo 14 Y 2 C 15 B 6 MG alloy on AISI 4140 SS substrate by laser processing with fine grains, uniform microstructure, high hardness and wear resistance. Wang et al. [17] deposited amorphous Ni 53 Nb 20 Ti 10 Zr 8 Co 6 Cu 3 alloy on carbon steel using kinetic metallization of atomized gas powders and reported that the corrosion resistance increases with coating thickness (400 μm) in 1 kmol/m 3 HCl. Similarly, amorphous Ni 59 Zr 20 Ti 16 Si 2 Sn 3 alloy deposited Surface & Coatings Technology 205 (2011) 3961–3966 ⁎ Corresponding author. Tel./fax: + 91 44 27480121. E-mail address: kamachi@igcar.gov.in (U. Kamachi Mudali). 0257-8972/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2011.02.039 Contents lists available at ScienceDirect Surface & Coatings Technology journal homepage: www.elsevier.com/locate/surfcoat