al 2 o 3 showed no preferred orientation sample d inserts from deposition in sample a were subjected to a heat treatment for 8 hours in flowing h 2 atmosphere this resulted in a transformation of u03ba al 2 o 3 to 100 u03b1 al 2 o 3 according to xrd analysis the u03b1 al 2 o 3 exhibited a texture coefficient tc of 1 5 of the 104 planes as well as of the 110 planes the inserts according to this example were then tested with respect to flank wear resistance in a longitudinal tuning operation of machining ball bearing steel similar to din 100 cr mo 6 the results are expressed in table 1 below as working time required to reach a predetermined flank wear of 0 3 mm on the cutting inserts table 1______________________________________ time to reach 0 3 mm flank wear in minutessample coating test 1 test 2______________________________________ u03ba al sub 2 o sub 3 210 22 5 22 5 invention b u03ba al sub 2 o sub 3 013 15 17 5 c u03b1 u03ba al sub 2 o sub 3 15 15 d heat treated sample a 15 17 5______________________________________ sample e cemented carbide cutting inserts with the composition 5 5 by weight co 8 6 by weight cubic carbides and balance wc as.