Journal of Alloys and Compounds 396 (2005) L4–L6 Letter Preparation of Ni–Mo–Fe alloys from MoO 3 concentrate using an electro-slag refining (ESR) method K. Jamshidi a , H. Abdizadeh a,∗ , S.A. Seyyed Ebrahimi a , K. Hanaei b a Department of Metallurgy and Materials, Faculty of Engineering, University of Tehran, Tehran 11365, Iran b Research Group of Metal Materials, Iranian Academic Centre for Education Culture and Research, Northern Kargar Ave., Faculty of Engineering, University of Tehran, Tehran, Iran Received 11 May 2004; received in revised form 18 December 2004; accepted 21 December 2004 Available online 23 January 2005 Abstract In this work a new method of Ni–Mo–Fe alloying using MoO 3 scrap has been presented. By using a proper amount of Al–50% Si as reductant, a mixture of CaF 2 , CaO, Al 2 O 3 and MgO as slag, CaO + 20% CaF 2 as flux and utilizing an ESR furnace; metalothermic reduction of MoO 3 , alloying Mo with Ni and Fe and refining of it can be achieved simultaneously, with about 92% efficiency and maximum solubility of Mo in Ni (35%) in solid state. The ability of using commercial molybdenum trioxides instead of pure molybdenum to make alloys with good efficiency will highly reduce the cost of the product. Making Ni–Mo–Fe alloys with different amounts of Mo and Fe has also been characterized by SEM techniques. © 2004 Elsevier B.V. All rights reserved. Keywords: Ni–Mo–Fe alloying; Metalothermic reduction; ESR; MoO 3 1. Introduction Ni–Mo alloys have various applications in many industries particularly in high temperature corrosion resistance tech- nologies [1–3]. Addition of Fe to these alloys can enhance the mechanical properties of the material [4]. The common method for making Ni–Mo–Fe alloys is us- ing pure molybdenum, nickel and iron, melting them by using an electron beam and alloying them together [5]. The electro- slag refining process is a secondary refining method with the ability of making dense, clean and pure products [6–8]. Al- though the ESR method is commonly used for refining metals but it has a great capability for making different alloys with good purity as well [9]. There are also many reports on the reduction of molybde- num trioxides by aluminum and silicon compounds [10–12]. Reduction of MoO 3 by mixture of Al and Si is done by reac- ∗ Corresponding author. E-mail address: abdizade@ut.ac.ir (H. Abdizadeh). tions (1) and (2). MoO 3 + 2Al → Mo + Al 2 O 3 (1) MoO 3 + 3 2 Si → Mo + 3 2 SiO 2 (2) These reactions are strongly exothermic and do not need extra heating [13]. In this work a novel method have been developed to make Ni–Mo–Fe alloys by using MoO 3 concentrates in an ESR furnace. 2. Experimental procedure Pure nickel as rolled and welded with pure iron was used as electrode. Instead of pure molybdenum, MoO 3 concentrate was used here for making alloys. The reductant material was Al–50% Si powder, which was milled before to a size of –50#. The composition of the slag is shown in Table 1. MoO 3 con- centrate with Al–50% Si powder and 10 wt.% of CaO + 20% CaF 2 were mixed together completely and pressed as cylin- 0925-8388/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2004.12.026