Effect of Cr on eutectic phase formation and solidification temperature range in Ni–Cr–Hf system

Abstract

In order to obtain eutectic phases which are beneficial for reducing ductility dip cracking and solidification cracking susceptibility in Ni-base alloys during non-equilibrium solidification (such as welding), samples with Ni–5Hf and different Cr levels were made using a button melting method. The relevant eutectic phases in the Ni–Cr–Hf system were identified. The solidification temperature range (STR) was determined by experimental Single Sensor Differential Thermal Analysis. It was found that γ/Ni5Hf eutectic formed in the Ni–0Cr, Ni–5Cr and Ni–10Cr system, while γ/Ni7Hf2 eutectic formed in the Ni–20Cr and Ni–30Cr system. Formation of the γ/Ni7Hf2 eutectic was responsible for a narrower STR, which indicates a better resistance to solidification cracking.