Hydrogen embrittlement resistance of GRCop-84

Copper-based alloys for structural high-heat-flux applications: a review of development, properties, and performance of Cu-rich Cu–Cr–Nb alloys

“…By adding an excess of Cr, the activity of Nb is reduced along with the risk of hydrogen embrittlement [98,100]. Ellis and Hastings performed tensile, notched tensile, stress, rupture, and LCF tests on extruded GRCop-84 in high pressure environments including high pressure H 2 , high pressure He, and samples charged in high pressure H 2 for 8 h at 922 K [99]. They were unable to find evidence of the formation of hydrides by either optical or (b) LCF plastic strains; (c) LCF stress range; RT -673 K and RT -873 K indicate that data has been combined from these temperatures to produce these trend lines (as there was no discernible difference in trend between them); redrawn with permission.…”

“…electron microscopy, changes in fracture morphology, or statistically significant difference in the mechanical tests [99]. The susceptiblility may change slightly between GRCop alloys and fabrication methods and should be tested, but ultimately, the H embrittlement is largely dependent on the Nb content that is available.…”

“…GRCop-84's thermal conductivity compared to similar high-heat-flux alloys is its weakest property due to its high alloying content and can be significantly impacted by impurities In 2000, Ellis and Keller with Thermophysical Properties Research Laboratory (TPRL), Inc. in West Lafayette, IN [93] calculated thermal conductivity and electrical resistivity of extruded GRCop-84 using the Kohlrausch method. Since both conductivity and resistivity are calculated, the Lorenz number could be determined and was measured between 29 and 480 K with 5 powder lots [93]. The Lorentz number was significantly higher than pure Cu's and demonstrated a mild temperature dependence, but these results had not taken Fe impurity into account and are not accurate to current GRCop-84 chemistry.…”

“…The Lorentz number was significantly higher than pure Cu's and demonstrated a mild temperature dependence, but these results had not taken Fe impurity into account and are not accurate to current GRCop-84 chemistry. Although the Lorenz number increased, Ellis and Keller believed that this was caused by the thermal conductivity increasing and electrical resistivity decreasing in response to the material dynamically annealing during the measurements [93]. So, it is possible that the Lorenz number is constant for GRCop-84, though an updated and more accurate measurement has not been acquired.…”

“…High volumes of liquid and high pressure gaseous hydrogen in the combustion chamber liner is a major concern. The Nb content of GRCop alloys is known to be the most susceptible component to embrittlement by forming a solid solution and hydrides with hydrogen [98][99][100]. Ellis et al [100] performed thermodynamic calculations with GRCop-84 based on activity and partial pressures.…”