bal d nickel molybdenum 83 00 10 00 bal e cobalt 83 20 100 f high chrome tool steel 34 50 85 10 00 3 00 bal g cobalt 90 100 __________________________________________________________________________ table ii shows certain of the physical characteristics of these composites and it describes their erosion mechanisms table ii__________________________________________________________________________ density hardness erosion ratei d g cc hrc cc g u00d7 10 6 erosion mechanism__________________________________________________________________________ a 5 77 74 2 2 08 matrix extrusion carbide fragmentation and ductile cuttingb 5 79 72 2 2 42c 5 21 77 7 0 96d 5 38 76 5 1 47 matrix extrusion carbide fragmentatione 5 35 75 8 1 17f 6 46 69 6 3 10 matrix extrusion ductile cutting and carbide fragmentationg 14 60 75 0 1 46 preferential binder erosion carbide__________________________________________________________________________ fracture table iii______________________________________alloy erosion rate cc g u00d7 10 sup 6 ______________________________________a 2 08b 2 42c 0 96d 1 47e 1 17f 3 10g 1 46 ______________________________________ it will be observed that the erosion rates of examples a b and f tic in tool steel greatly exceed the rates of examples c d and e all of which have a much higher tic volume percentage by way of comparison example g cobalt and wc equals the performance of example d but is much less resistant than examples c and e here it may be commented that the density of examples c d and e are 5 21 5 38 and 5 35g cm 3.