Evaluation of Methods to Produce Tough Cr₃Si Based Composites

Several methods of improving the toughness of Cr-Cr ₃ Si 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 Cr ₃ Si 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 Cr ₃ Si. These include an Fe-Al alloy, Ni ₃ Al + 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 ₃ Si composites were hot forged to produce a more layered microstructure and refine the micro structure of arc-melted samples. The layered micro structure should be tougher, but has not been tested yet.