POWDER METALLURGY DEVELOPMENT

TITANIUM ALLOYS ARE USED IN HIGH PERFORMANCE AEROSPACE COMPONENTS DUE TO THEIR UNIQUE COMBINATION OF HIGH STRENGTH-TO-DENSITY RATIO AND EXCELLENT CORROSION RESISTANCE. THE EVER INCREASING DEMAND FOR STRONGER AND LIGHTER ALLOY FOR AIRBORNE APPLICATIONS REQUIRES NEW TITANIUM ALLOYS WITH USEABLE STRENGTH LEVELS EXCEEDING 200KSI. THIS PROPERTY GOAL REQUIRES A SIGNIFICANT IMPROVEMENT OVER THE PRESENT ALLOYS LIKE TI-10V-2FE-3AL, AND REPRESENTS A 60% INCREASE OVER THE STRENGTH OF ANNEALED TI-6AL-4V ALLOY. IT IS PROPOSED TO MEET THIS OBJECTIVE BY DEVELOPING NEW RAPIDLY SOLIDIFIED TERNARY AND HIGHER ORDER ALLOYS BASED ON THE EUTECTOID-FORMING TI-CU SYSTEM. IT IS EXPECTED TO ACHIEVE A COMBINATION OF STRENGTHENING MECHANISMS INCLUDING SOLID SOLUTION HARDENING, PRECIPITATION HARDENING AND GRAIN BOUNDARY STRENGTHENING. THE PROPOSED ALLOYS HAVE SHOWN PROMISE FOR ACHIEVING A COMBINATION OF VERY HIGH STRENGTH AND DUCTILITY WHEN THE PRECIPITATE SIZE AND SPACING ARE CAREFULLY CONTROLLED. IT IS PROPOSED TO CONDUCT AGING HEAT TREATMENTS ON RAPIDLY SOLIDIFIED PARTICULATES OF THESE ALLOYS TO DETERMINE PROCESSING CONDITIONS CORRESPONDING TO OPTIMUM MICROSTRUCTURE AND PROPERTIES. THIS WORK WILL BE SUPPORTED BY MICROHARDNESS MEASUREMENTS AND A DETAILED MICROSTRUCTURAL CHARACTERIZATION USING SCANNING TRANSMISSION ELECTRON MICROSCOPY AND X-RAY ENERGY DISPERSIVE SPECTROSCOPY.