Insights into the development of Fe modified Ti-Nb alloy: A powder metallurgy perspective

Abstract

This study explores a cost-effective method for fabricating Ti95-xFexNb5 ternary alloys along with investigating the influence of Fe addition. Spark Plasma Sintering at low sintering temperatures followed by heat treatment was used to obtain fully dense and homogenized compacts. Initially for composition with 0% Fe by weight, a Widmanstätten microstructure was observed along with coarse α plates that nucleated on the grain boundaries. The addition of Fe refined the microstructure reducing the size of α plates. The solute-drag effect of Fe led to a progressive decrease in parent β grain size. In alloy with 10% Fe by weight, Widmanstätten structure transformed into β grains while α phase nucleation was greatly suppressed. Moreover, the incorporation of Fe in β phase lattice led to a strong partitioning effect at microstructural level and lattice distortion effect at atomic level. These factors resulted in a pronounced strengthening of the alloy increasing the hardness and tensile strength. However, these factors also led to the embrittlement of the composition containing 10% Fe by weight. The study highlight the potential of powder metallurgy approach which offers avenues for cost efficient Ti alloy production. However, incorporation of high Fe concentrations should be paralleled with careful microstructural design.