  Oblique interaction of small- but finite-amplitude KdV-type electron-acoustic
solitary excitations is examined in an unmagnetized two-electron-populated
degenerate quantum electron-ion plasma in the framework of quantum
hydrodynamics model using the extended Poincar\'{e}-Lighthill-Kuo (PLK)
perturbation method. Critical plasma parameter is found to distinguish the
types of solitons and their interaction phase-shifts. It is shown that,
depending on the critical quantum diffraction parameter $H_{cr}$, both
compressive and rarefactive solitary excitations may exist in this plasma and
their collision phase-shifts can be either positive or negative for the whole
range of the collision angle $0<\theta<\pi$.
