Evaluation of methods to produce tough Cr3Si based composites

Several methods of improving the toughness of Cr-Cr3Si composites produced by powder metallurgy have been examined. Mechanical alloying of Cr-3.92 w/o with 0.5 w/o V showed the best improvement in toughness of this phase. Replacing Cr3Si with a (Cr-0.57, Mo-0.43)(3)Si, produced in situ from a mechanically alloyed powder, offered a slight improvement in toughness. By combining these phases a composite was produced with a toughness greater than 10 MPa m(-2). Other second phase materials were also examined for providing second phase toughening of Cr3Si. These include an Fe-Al alloy, Ni3Al + B, and 304L stainless steel. At the level of 25 v/o these materials at present do not appear to offer much improvement in toughness. Cr-Cr,Si composites were hot forged to produce a more layered microstructure and refine the microstructure of are-melted samples. The layered microstructure should be tougher, but has not been tested yet. (C) 1997 Elsevier Science S.A.