H. L. Fraser, P. Collins, Center for Accelerated Maturation of Materials, Columbus, OH; D. Hill, R. Banerjee, The Ohio State University, Columbus, OH; J. Tiley, Air Force Research Laboratory, Wright-Patterson, AFB, OH

Summary:

Due to their wide applicability, there is considerable interest in the development of metalmatrix composites consisting of hard precipitates, such as transition-metal borides, dispersed in a metallic/ alloy matrix. One such system that has generated considerable interest in recent years is the titanium boride in titanium alloy matrix system. Laser engineered net-shaping (LENS™) is a directed laser deposition process which uses a powder feedstock and appears to be a promising technology for the processing of these metal-matrix composites. Two types of TiB reinforced composites have been studied, one with an a+b matrix based on the alloy Ti- 6Al-4V and the other with a primarily b matrix based on the alloy Ti-5Al-5V-5Mo-3Cr-0.5Fe (TIMETAL 5553). Using a feedstock consisting of a blend of pre-alloyed Ti-6Al-4V (or TIMETAL 5553) and elemental boron powders, these composites have been deposited in a single step via the LENS™ process. These asdeposited composites exhibit a refined homogeneous distribution of TiB precipitates within the alloy matrix, a consequence of the rapid solidification rates inherent to the LENS™ process. The microstructure of the LENS™ deposited composites has been investigated in detail using SEM and TEM based techniques. The room temperature tensile properties and wear resistance of these composites is currently being investigated and will be presented in this paper.