Preparation of a hard AlTiVCr compositionally complex alloy by self-propagating high-temperature synthesis

In this study, an AlTiVCr compositionally complex alloy with a high hardness of 865 +/- 34 HV was prepared by a one-step self -propagating high -temperature synthesis (SHS) method using TiO 2 , V 2 O 5 , Cr 2 O 3 , and Al as starting materials. Experimental results confirmed the formation of a two-phase alloy having BCC solid solution dendritic grains reinforced by a Ti -rich intermetallic phase. Elemental analysis results confirmed that the Ti at.% in the synthesized alloy was lower than other elements. The addition of extra TiO 2 to the reactants, pre -milling of the TiO 2 -Al mixture, and using the Rutile polymorph of TiO 2 instead of Anatase as the starting material increased the atomic percent of Ti. The composition of the proper synthesized alloy was formulated as Al 27.3 Ti 17.2 V 28.7 Cr 26.8 which is close to the desired AlTiVCr alloy. To clarify the reaction sequence during the SHS, the binary mixtures were analyzed by thermal analysis. It was postulated that the melting of Al facilitated the reduction reaction of Cr 2 O 3 and V x O y compounds, while TiO 2 was the last oxide compound reduced by Al. This hindered the completion of the TiO 2 reduction reaction and as a consequence, the unreacted TiO 2 entered the slag which lowered the concentration of Ti in the composition of the final alloy.