Effect of rare earth addition on diffusion kinetics of borided TC21-DT titanium alloy

Abstract

In this study, the properties and growth kinetics of boride layers, generated on the surface of TC21-DT alloy using appropriate amount of powders of boron carbide (B4C) and rare earth oxide (CeO2) were investigated. By conducting a series of experiments at different temperatures of 1123, 1223 and 1273 K for periods up to 10 h, the effects of rare earth (RE) addition on the growth kinetics of boride layers were studied. The characteristics of the boride layers were examined by scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction and micro-Vickers hardness tester. The results showed that the boron diffusion in boride layers was obviously accelerated by RE addition and the activation energy for RE addition-boriding in TC21-DT alloy was greatly decreased to 58.13kJ/mol, which was approximately 40% lower than that of conventional one, without RE addition.