Combustion Synthesis of FeAl-based Composites from Thermitic and Intermetallic Reactions

C.l Yeh ,Chih-Yao Ke

doi:10.3390/cryst9030127

Abstract

Combustion syntheses involving intermetallic and thermitic reactions were conducted to fabricate FeAl–TiB2–Al2O3 composites. Two combustion systems consisting of Fe, Al, Ti, Fe2O3 and B2O3 were studied for formation of xFeAl–yTiB2–Al2O3 composites with x = 1.5–3.5 and y = 0.5–0.8. In the reaction series, thermitic reduction of Fe2O3 and B2O3 by Al thermally activated the reaction between Fe and Al. As a result, the combustion wave of the synthesis reaction was sufficiently exothermic to propagate in a self-sustaining manner. With an increase in TiB2 and FeAl of the composites, the decrease of reaction exothermicity resulted in a decline of the combustion wave velocity and reaction temperature. The activation energy Ea = 88.92 kJ/mol was deduced for the synergetic combustion reaction. Based on XRD analysis, a thorough phase conversion was achieved and composites composed of FeAl, TiB2, and Al2O3 with different contents were obtained. The SEM micrograph showed the FeAl-based composite with a dense and connecting morphology.

Highlights

Aluminides of transition metals such as titanium, iron, nickel, and niobium are recognized by their excellent physical and mechanical properties [1,2,3]
Two combustion systems of different stoichiometries were formulated for synthesis of FeAl–TiB2 –Al2 O3 composites and expressed as Reactions (1) and (2)
It is apparent that well-defined combustion wave develops upon and Billerica, traversesMA, the

Summary

Introduction

Aluminides of transition metals such as titanium, iron, nickel, and niobium are recognized by their excellent physical and mechanical properties [1,2,3]. Among these compounds, iron aluminides (FeAl and Fe3 Al) are of considerable interest for high-temperature structural applications, due to their inexpensive raw materials, high melting point, low density, and outstanding resistance to corrosion at elevated temperatures under oxidizing, sulfidizing, and carburizing atmospheres [1,4,5,6]. The addition of ceramic components, such as TiB2 , TiN, TiC, WC, Al2 O3 , and ZrO2 , as reinforcement has proven to effectively improve the room-temperature mechanical properties in nickel and iron aluminides, their wear resistance and high-temperature strength without degrading the inherent oxidation resistance [11,12,13,14,15]

Objectives

Methods

Results

Conclusion