Hot deformation behaviors and processing maps of B4C/A16061 neutron absorber composites

In this study, the hot deformation behaviors of 30 wt.% B4C/A16061 neutron absorber composites (NACs) have been investigated by conducting isothermal compression tests at temperatures ranging from 653 K to 803 K and strain rates from 0.01 to 10 s(-1). It was found that, during hot compression, the B4C/A16061 NACs exhibited a steady flow characteristic which can be expressed by the Zener-Hollomon parameter as a hyperbolic-sine function of flow stress. High average activation energy (185.62 kJ/mol) of B4C/A16061 NACs is noted in current study owing to the high content of B4C particle. The optimum hot working conditions for B4C/A16061 NACs are found to be 760-803 K/0.01-0.05 s(-1) based on processing map and microstructure evolution. Typical material instabilities are thought to be attributed to void formation, adiabatic shear bands (ASB), particle debonding, and matrix cracking. Finally, the effect of the plastic deformation zones (PDZs) on the microstructure evolution in this 30 wt.% B4C/A16061 composite is found to be very important. (C) 2016 Elsevier Inc. All rights reserved.