Low temperature physical properties of a Ni-Mo-Cr alloy Haynes® 242™

Abstract

Haynes 242 is a Ni-Mo-Cr based superalloy. High strength and high fracture toughness at low temperatures make Haynes 242 an attractive choice for cryogenic applications such as the conduit material for the cable-in-conduit conductor of superconducting magnets. In this work, its low temperature physical properties including magnetization, specific heat, electrical resistivity, thermal conductivity, and Seebeck coefficient are measured from 2to300K. Haynes 242 shows Curie paramagnetism with a Curie constant C=0.0289K. The electrical resistivity has a minimum at ∼12K and shows weakly linear T dependence at high temperatures as expected. The specific heat Cp between 10 and 40K can be fitted by Cp=γT+AT3 with γ=9.43×10−5J∕gK2 and A=5.91×10−7J∕gK4. Below 10K, an upturn in Cp∕T with decreasing T is interpreted by the existence of very small ferromagnetic clusters which is supported by our magnetization data. The thermal conductivity is analyzed by separating the electronic and phonon contributions. The relatively strong phonon thermal conduction at temperatures <100K results in effective Lorenz number a few times larger than the ideal Lorenz number. Our results suggest that Haynes 242 is suitable for many cryogenic applications including conduit for large superconducting magnet and low temperature probe.