  We investigated the vortex phase diagram of needle shaped high quality NiBi3
single crystals by transport measurements. The current is applied along the
crystalline b-axis of this intermetallic quasi-1D BCS superconductor. The
single crystals show a Ginzburg-Levanchuk (Gi) parameter few orders of
magnitude larger than other low Tc BCS superconductors. Vortex phase diagram,
critical currents and pinning forces have been extracted from the experimental
data. The main findings are: 1) Enhancement of the vortex liquid phase in
comparison with low Tc superconductors, 2) reentrance of the liquid phase at
low fields and 3) deviation of the pinning force vs field from the usual
pinning mechanisms. The interplay between weak pinning, due to quenched
disorder, and the quasi-1D character of the material could be a hint to explain
the lack of a single pinning mechanism.
