Axis.MajorTickMark (Excel)
Returns or sets the type of major tick mark for the specified axis. Possible return values are xlTickMarkCross - Crosses the axis, xlTickMarkInside - Inside the axis, xlTickMarkNone - No mark, xlTickMarkOutside - Outside the axis.
XlTickMark can be one of the XlTickMark constants.
ActiveChart.Axes(1).MajorTickMark = xlTickMarkCross