Microstructure control and tensile properties of three-phase alloys based on the E2(1) Co3AlC and B2CoAl

To investigate tensile mechanical behavior, tensile tests were conducted at room temperature and 1273 K on three-phase alloys consisting of the E2(1) Co3AlC, B2 CoAl and (Co) primary solid solution. The alloy containing a lar ge volume fraction of E21 phase exhibits excellent ductility, exceeding 5% plastic strain at room temperature, while the alloy with a,considerable amo unt of coarse B2 phase particles shows zero ductility. In this study, micro structure control was used to improve the ambient temperature ductility of the E2(1)/B2/(Co) three-phase alloys. Hot forging and subsequent heat treat ments were performed aiming at eliminating solidification defects and minim izing the heterogeneity of the as-cast microstructure. These thermomechanic al treatments together with compositional control effectively improve the d uctility of the E2(1)/B2/(Co) three-phase alloys at ambient temperature and 1273 K. (C) 2001 Elsevier Science Ltd. All rights reserved.