Boron – Iron – Titanium

Abstract

The study of B-Fe-Ti alloys was triggered by the development of Fe based alloys with high wear resistance that can be used as coating materials, TiB2-reinforced high modulus steels, cutting materials and titanium based metal-matrix composites. [1974Shu] reported a quasibinary section along the Fe-TiB2 join. A eutectic temperature of 1340°C and the eutectic composition of about 7 mol% TiB2 have been proposed. These results were consistent with an isothermal section for 1000°C presented by [1967Fed] who showed that TiB2 formed two-phase regions with all phases existing in the Fe-Ti and B-Fe binary border systems. Phase equilibria and solidification of B-Fe-Ti alloys in the region close to Fe-TiB2 have been studied by [1992Ott]. [1999Tan] performed thermodynamic calculations of the Fe-TiB2 equilibrium, supplemented with a limited experimental study. The calculations were carried out with and without considering the effect of the typical impurities found in the starting materials used in their powder metallurgical processing route. The isothermal section for 1000°C computed by [1999Tan] without including impurities shows that the (Fe)+TiB2 twophase equilibrium is shifted to the Fe-Ti border. This feature coincides with the experimental results of [1992Ott]. These investigations [1992Ott, 1999Tan] were reviewed by [2003Rag]. As mentioned above, B-Fe-Ti alloys may be used as material for the manufacture of cutting instruments. [1961Fun] studied Vickers hardness, the transverse strength and wear resistance of Fe-TiB2 alloys produced by pressing and high temperature sintering as a function of composition and technological route. [1966Yas] studied the wetting of TiB2 by liquid Fe. [1966Has] studied the influence of alloying with 0.2 mass% Ti on the peritectoid reaction temperature, Vickers hardness, and UTS of Fe-0.2 mass% B. It was shown, that alloying with Ti raises the peritectoid reaction temperature from 912 to 923°C, but this result was obtained on an alloy contaminated by 0.15 mass% Si and 0.2 mass% Mn. [1972Tic] presented results of wear resistance studies of Fe-TiB2 alloys with different volume fractions of the boride. It was shown that the best wear resistance is exhibited by the eutectic composition alloy, which has a regular structure. The presence of primary crystals of the soft α(Fe) in hypoeutectic alloys leads to a increase in the total wear owing to high wear of specimen. If the tested specimen has the hypereutectic composition and coarse TiB2 primary are present in structure, the increase in the total wear is caused by wear of the counterpart. Mechanical properties of the eutectic alloy with Fe-6.3 mass% TiB2 has been studied by [1977Shu]. Structure and mechanical properties of some B-Fe-Ti alloys have been studied by [2005Lou]. [1982Yur] studied the changes taking place in the fine structure of TiB2 during vibratory milling and subsequent liquid-phase sintering of the TiB2-Fe(Mo) cermet. Mo was added to improve the wetting of TiB2 grains by the melt formed during sintering. [1985Mak] presented the possibility of producing Fe-TiB2 cermets using a self-propagation hightemperature synthesis (SHS) route. [1995Ras] studied the dependencies of TiB2 formation under SHS and the hardness of cermets produced on using different Fe:TiB2 ratios. It was shown that irregularities in the plots of the amount of TiB2 and hardness with respect to green composition corresponded to the Ti/Fe ratio in the eutectic β(Ti)+TiFe and the B/Fe ratio in the eutectic FeB+FeBn. The mechanism of phase changes in the B-Fe-Ti system following a combustion wave during SHS processing for a mixture of Ti, B, and Fe powders and a ferroboron alloy-titanium mixture with the same proportion of elements has been studied by [2000Lep, 2004Lep]. The kinetics of phase transformation and wear resistance of in-situ processed titanium matrix composites based on B-Fe-Ti has been studied by [1999Bra]. The sintering parameters employed when using the powder metallurgical route were improved with the aim of increasing wear resistance. [1991Dud] presented magnetic properties and crystallization temperatures of magnetic glasses of Fe80–xTixB20 (x = 6, 10, and 20 at.%).