Abstract: Compositions suitable for use in an electrolytic cell for producing aluminum are provided. The compositions can contain a powder blend of boron oxide, a titanium dioxide, aluminum, and titanium diboride. The powder blend can be compacted into tiles and arranged as a cathode surface. The boron oxide and the titanium dioxide in the tiles can be made to react under low temperature molten aluminum to produce titanium diboride in situ. The reaction yields a dense dimensionally stable wettable cathode substrate that can reduce the power consumption in the aluminum electrowinning process.