1 NICKEL-CHROMIUM-BORON ALLOYS PRODUCTION BY ALUMINOTHERMIC PROCESSES Özge Caglar Yilmaz, Murat Alkan, Onuralp Yücel Istanbul Technical University, Faculty of Chemical & Metallurgical Engineering, Metallurgical and Materials Engineering Dep., ITU Ayazaga Campus, Maslak, 34469, Istanbul, Turkey Keywords: Intermetallics, Ni-based alloys, Cr-based alloys, Metallothermic process Abstract In this study, Ni-Cr-B alloys were synthesized using a mixture of NiO-Cr 2 O 3 -B 2 O 3 powders reducing with Al powders by a metallothermic process which is a high energy efficient, fast and low-cost production technique for synthesis of cast alloys. Detailed thermodynamical studies were simulated by using FactSage 6.2 Thermochemical software in order to calculate adiabatic temperature of the reactions and effects of initial molar composition on the final products. In the SHS experiments, effects of initial mixture ratios (NiO:Cr 2 O 3 :B 2 O 3 ) on the metal recovery and compositions of final alloys were carried out. Final products were characterized by using AAS, XRD, EPMA and microhardness techniques. Introduction Self Propagating High Temperature Synthesis (SHS) has significant advantages compared to the high technology furnace applications, such as very short processing time, simple operation, low energy requirement and low cost [1, 2]. In a SHS process, the ignition starts the combustion and propagates throughout the reactant mixture yielding the desired product [3, 4]. However, the disadvantages of the process such as inhomogeneous or unreacted products due to undesirable reaction rates needs to be overcome by changing some parameters such as ignition temperature, particle size, additive, atmosphere etc. The earliest studies on Ni-Cr-B alloys were started with the boron additives into the Cr-Ni brazing alloys which led to decrease the melting temperature of these alloys [5]. In this study, effect of initial mixture compositions on SHS process, metal recovery and alloy compositions were examined. Experimental Procedure In the SHS experiments, NiO, Cr 2 O 3 , B 2 O 3 and Al powders were used in order to produce Ni- Cr-B alloy. The raw materials have over 96 % purity and 200 μm average grain sizes. The initial mixtures were calculated and prepared to produce alloy containing 80-15% Ni, 15-80% Cr, and 5% B by weight. The advanced thermochemical simulations of the reactions were investigated in detail including different ratios of initial mixtures, and their effects on metal recoveries, metal distributions and alloy compositions were carried out. The reaction mixtures were mixed thoroughly 15 minutes in a turbula mixer and powder mixtures (approximately 150 g) were charged into Cu crucible and compacted. Cr-Ni wire was placed at the top of copper crucible and the reaction realized by passing current through the wire. 335 Ni-Co 2013 Edited by: Thomas Battle, Michael Moats, Violina Cocalia, Harald Oosterhof, Shafiq Alam, Antoine Allanore, Rodney Jones, Nathan Stubina, Corby Anderson, and Shijie Wang TMS (The Minerals, Metals & Materials Society), 2013