Synthesis of Mo(Si,Al)(2) alloy by reactive hot pressing at low temperatures for a short time

Mo(Si,Al)(2) alloy was prepared by reactive hot pressing at low temperature s for a short time under 20 MPa in a vacuum using MoSi2, Mo and Al as start ing powders. At 1160 degrees C, 5 min of soaking time was enough to obtain a high density alloy. At 1060 degrees C however, 10 min was needed. The for mation of Mo(Si,Al)(2) was accompanied by the melting of aluminum and contr olled by the dissolution of molybdenum into the aluminum melt. It was propo sed that the oxygen present in MoSi2 raw powder would react with aluminum a nd form Al2O3 in an amorphous or poor crystallization state. The mechanical properties of the alloy were a little stronger than those of monolithic Mo Si2 alloy. The formed Al2O3 particles acted as crack-pinning elements, but a large toughening effect could not be obtained by this crack-pinning becau se of the strong interface bonding and the similar thermal expansion coeffi cients of Mo(Si,Al)(2) and Al2O3. (C) 1999 Kluwer Academic Publishers.