Effect of molybdenum addition on mechanical properties of oriented bulk Fe 2 B crystal

  • PDF / 978,848 Bytes
  • 9 Pages / 584.957 x 782.986 pts Page_size
  • 17 Downloads / 224 Views

DOWNLOAD

REPORT


fects of Mo addition on the microstructure, mechanical properties, and abrasive wear properties of an oriented bulk Fe2B crystal have been investigated systematically in the present paper. Five groups of pure Fe2B samples with different Mo contents have been examined by optical microscope, X-ray diffraction, scanning electron microscope integrated with energy disperse spectroscopy, microhardness tester, and three-point bending testing of fracture toughness. The results indicate that Mo tends to segregate on the grain boundaries after doping; with increasing Mo addition, interplanar spacing of the (002) crystal plane of Fe2B decreases firstly and then increases slightly while that of (200) increases gradually; microhardness on the transversal section changes little while that on the longitudinal section increases firstly and then decreases [possessing the opposite trend to interplanar spacing of (002)]; fracture toughness and wear resistance of both transversal and longitudinal samples can be improved to some extent with Mo addition less than 2.0 wt%. In conclusion, appropriate Mo addition plays a positive role in the improvement of mechanical properties of oriented bulk Fe2B.

I. INTRODUCTION

Recently, Fe–B alloy attracts many researchers’ attention for its capacities on wear resistance and corrosion resistance in zinc melt.1–5 In the Fe–B alloy, the hard Fe2B phase acting as the reinforcement phase plays an important role in comprehensive properties of the alloy. Compared with traditional Fe–C cast alloys, Fe2B in the Fe–B alloy has the advantage of high hardness, good thermostability, and corrosion resistance, which is superior to the Fe3C hard phase. However, Fe2B has intrinsic embrittlement due to the weak B–B bond along [002] crystal orientation.6–9 For industry applications with impacts, Fe2B tends to fracture causing premature failure to the component, which may bring catastrophic loss. To guarantee the performance and safety of application, many researchers have explored various ways to improve the comprehensive properties of the Fe–B alloy.1,3,11–17 Yi1,14 has found that with titanium, nitrogen, and cerium addition the network microstructure of Fe2B can be refined and wear properties of the Fe–B alloy can be improved. Additionally, Ma13 and Liu12 have reported that the microstructure and mechanical properties of the Fe–B alloy can be ameliorated by appropriate chromium addition. Their results have given

Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.41

the messages that transition metal element can make contribution to the improvement of the microstructure and mechanical properties of the Fe–B alloy. In my previous researches,9,17,18 the effects of chromium and manganese addition on mechanical properties and wear properties of the Fe–3.0 wt% B alloy have been explored. All these reports imply that mechanical properties of Fe2B play an important role in the application of the Fe–B alloy. In addition, Ma19 and Wang5 have propo