references:
  - J.G. Hust and A.B. Lankford,
    Thermal Conductivity of Aluminum, Copper, Iron, and Tungsten from 1K to the Melting Point,
    US Department of Commerce, Boulder, Colorado, 1984,
    fit to Tab. 2.4.1 (RRR=1000, T_min=200K, T_max=1000K)
  - https://www.mit.edu/~6.777/matprops/copper.htm

K_11: 4.039e+2
K_11,T: -8.119e-2
K_11,T^2: 1.454e-5

T_ref: 293.15

C_p: 385.0