JimMetalsCeramics,
How can you say that AerMet alloys lack fracture toughness? They are among the toughest materials available. For example, with ultimate tensile strength of 1700 MPa, the fracture toughness is 150 MPa m0.5. With ultimate tensile strength of 2100 MPa, the fracture toughness is 60 MPa m0.5. There really aren't many other options for high strength, high toughness materials.
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.