Compressive mechanical properties of multi-phase alloys based on B2CoAl and E2(1) Co3AlC

Mechanical behavior of multi-phase alloys, consisting of intermetallic comp ounds B2 type CoAl and E2(1) type Co3AlC with primary solid solution (Co), was investigated by compression tests over a wide temperature range from 77 to 1273 K. It has been revealed that E2(1) Co3AlC is a good candidate of c oexisting phase with B2 CoAl to improve the alloy's ambient temperature duc tility and its elevated temperature strength. Most of the multi-phase Co-Al -C ternary alloys exhibit fairly good compressive ductility at whole test t emperatures, even at 77 K. All the alloys show the anomalous positive tempe rature dependence of strength at intermediate temperatures. The deformation mechanism of E2(1) Co3AlC is expected to be the same as that of L1(2) inte rmetallic compounds because of the close resemblance of their crystal struc tures. The three-phase B2/E2(1)/(Co) alloy, 70Co20Al10C(at%), exhibits exce llent ductility of virtually unlimited ambient temperature compressive plas tic strain and the highest strength around 340 MPa at 1273 K. (C) 2000 Else vier Science Ltd. All rights reserved.