Alloy design and microstructural evolution in V–Ti–Cr alloys

Abstract

V-alloys in combination with Ti and Cr have been identified as potential candidate materials for various energy technologies as an alternative to fossil fuel based technologies. Phase formation and microstructural evolution in ternary V–Ti–Cr alloys along with the constituent binaries have been studied by Miedema approach and the selected binary and ternary alloy compositions have been studied experimentally in order to validate the results obtained from Miedema's model. According to Miedema's model V–Ti–Cr ternary alloys in the V-rich side of the phase diagram should form a solid solution phase and the ternary alloy composition in the vicinity of binary TiCr2 Laves phase should form amorphous or intermetallic phase. The expected solid solution phase in binary V–Ti and V–Ti–20Cr alloy system may undergo phase separation. Four alloy compositions, as identified by the Miedema approach e.g., V–4Ti–4Cr, V–39Ti–54Cr, V–50Ti and V–40Ti–20Cr, have been studied experimentally. V–4Ti–4Cr alloy forms BCC solid solution phase upon solidification. In V–39Ti–54Cr alloy, V-substituted cubic TiCr2 Laves phase is seen upon solidification. The BCC solid solution phase in binary V–50Ti and ternary V–40Ti–20Cr alloys undergoes phase separation giving rise to V-rich and V-poor domains. In the ternary V–40Ti–20Cr alloy, the phase separation is essentially binary as Cr is distributed homogeneously in the phase separated domains. Interesting possibilities exist for V–Ti–Cr alloys so far as phase transformation, microstructural evolution and tailoring of properties are concerned. Moreover, Miedema's approach could be used to design alloys in this system.