Journal of Alloys and Compounds 483 (2009) 168–172 Contents lists available at ScienceDirect Journal of Alloys and Compounds j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j a l l c o m Processing and characterization of rapidly quenched Ti-based alloys: Influence of solidification rate on the as-quenched structures H. Lefaix a,∗ , P. Vermaut a , D. Janickovic b , P. Svec b , R. Portier a , F. Prima a a Laboratoire de Physico-Chimie des Surfaces, CNRS–ENSCP (UMR 7045), Ecole Nationale Supérieure de Chimie de Paris, 11 rue Pierre et Marie Curie F-75231 PARIS cedex 05, France b Institute of Physics, Slovak Academy of Sciences, Dubravska Cesta 9, Bratislava, Slovak Republic a r t i c l e i n f o Article history: Received 30 August 2007 Received in revised form 8 July 2008 Accepted 15 July 2008 Available online 17 December 2008 Keywords: Rapid solidification Nanostructured materials Quasicrystals a b s t r a c t From technological viewpoint,icosahedral Ti–Zr–Ni phase may give challenging opportunities as novel hydrogen storage and hydride battery. Nevertheless, from the structural standpoint, the phase selection criterion as function of solidification route remains unclear. A series of Ti 45 Zr 38 Ni 17 alloys, known to pro- vide stable and well-ordered quasicrystals, was produced by planar flow casting using different processing parameters. From structural characterization, it appears that, at high cooling rate, i.e. high wheel speeds, or for the highest temperature of the melt, the as-quenched sample exhibits a mixture of nanoscale ␤ and amorphous phases. The icosahedral phase precipitates when decreasing the wheel speed, from lower temperatures of the melt or after annealing a crystallized amorphous matrix. The reproducible formation of quasicrystals, observed in the amorphous matrix containing ␤ particles, corroborates the competition between icosahedral and body-centered cubic (bcc) phases during the solidification process. These results are promising since it could be possible to control volume fractions of these two phases by choosing well- fitted thermal treatments so that quasicrystals mechanical properties should be improved by dispersion of a stable bcc phase. © 2008 Elsevier B.V. All rights reserved. 1. Introduction A large class of quasicrystals, long-range ordered materials with a forbidden rotational symmetry [1], can be prepared by rapid solid- ification routes. Among the various studied Ti/Zr-based systems, the ternary Ti–Zr–Ni alloy appears particularly interesting since it can promote the formation of a stable and well-ordered icosa- hedral phase [2–4]. From technological viewpoint, this may give challenging opportunities because of its ability to absorb consid- erable amounts of hydrogen [2,5]. A large body of work has been devoted to these novel materials, including several studies about elaboration routes.Ti–Zr–Ni quasicrystals have been mainly pre- pared by rapid quenching,e.g. melt spinning [3,6–8], or powder metallurgy [9]. However, the complex multiphase solidification structures of these compounds, strongly affected by processing parameters [11–12] and chemical composition [4,10], together with the coexistence of a great number of structural states such as approximants, solid solution or large-cell Laves phases [10], retard the development activities and the transfer to industrial tech- niques. In the present paper, we have considered the Ti 45 Zr 38 Ni 17 ∗ Corresponding author. E-mail address: helene-lefaix@enscp.fr (H. Lefaix). alloy, using a rapid solidification technique,i.e. planar flow cast- ing. Hence, a set of alloys has been investigated as a function of the melt solidification rate (wheel speed) as well as depending upon the initial temperature of the melt. As-quenched microstruc- tures have been extensively characterized both by X-ray diffraction (XRD) and transmission electron microscopy (TEM) in order to clar- ify the quasicrystals formation dependence upon processing routes involving rapidly solidified inherited structures. Preliminary ther- mal measurements, using differential scanning calorimetry (DSC), have been performed as well, in order to compare phase transfor- mations sequences upon heating. 2. Experimental procedures An ingot of Ti 45Zr 38Ni 17 was prepared by arc melting the appropriate amounts of commercially pure Ti (99.9%), Zr (99.9%) and Ni (99.9%) metals in an argon gas atmosphere. About 20 g as-cast ingots were turned out and re-melted four times in order to achieve chemical homogeneity. Rapidly solidified ribbons with 5–10 mm in width and 30–130 ␤m in thickness were obtained by planar flow casting on a rotating copper wheel using a quartz nozzle with controlled ejection temperatures of 1423 and 1573 K and wheel speeds of 10, 30, 36 and 40 m s −1 . The as-quenched ribbons were structurally characterized by X-ray diffraction (XRD) in a –2 diffractometer (Philips 1810) using Cu K␣ radiation ( = 0.15418 nm) and transmission electron microscopy (TEM) carried out in a JEOL-2000 EX micro- scope operating at 200 kV. TEM specimens were thinned by argon ion milling techniques. Phase transformations were monitored on ribbons quenched at 36 m s −1 from 1423 and 1573 K by differential scanning calorimetry (DSC) in a TA instrument thermal analyzer. 0925-8388/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2008.07.203