titanium-alloy powder. The rapid cool- ing that takes place during atomization results in a fine and uniform disper- sion of titanium carbide and titanium boride.
Research Summary
Ti-B Alloys and Composites
The Pre-Alloyed Powder Metallurgy of Titanium with Boron and Carbon Additions C.F. Yolton
Discontinuously reinforced titanium alloys have been produced by gasatomizing Ti-6Al-4V (in weight percent) with additions of boron and/or carbon to make a pre-alloyed, in-situ reinforced titanium-alloy powder. The rapid cooling that takes place during atomization results in a fine and uniform dispersion of titanium carbide and titanium boride. The atomized powder can be consolidated using standard titanium powder consolidation methods such as hot isostatic pressing or extrusion and further processed to produce standard mill forms. Mechanical properties of the consolidated product show roomtemperature tensile strengths up to 1,470 MPa with an elastic modulus of approximately 140 GPa. INTRODUCTION Titanium metal-matrix composites with continuous reinforcements are potential candidates for aerospace structural components and other structures requiring high strength, high stiffness, and low density. In recent years, a considerable amount of development
work has been conducted on discontinuously reinforced titanium composites, and significant progress has been made in developing this class of alloys.1–4 In comparison to continuously reinforced titanium composites, some of the advantages of discontinuously reinforced titanium composites are nearly isotropic properties, an ability to process the composite with conventional metalworking equipment, and dramatically reduced cost. Discontinuously reinforced composites can be made by co-spraying the reinforcement and the matrix5 or by blending the particulate reinforcement with a matrix material that is in either particulate or liquid form.6,7 Another way of making a discontinuously reinforced titanium-matrix composite is the in-situ method where the reinforcement is produced by formation or precipitation of a compound.8,9 This is the method used to make the pre-alloyed powder reinforced with titanium boride (TiB) and/or titanium carbide (TiC) described in this article. To produce the in-situ reinforced pre-alloyed titanium powder,
boron and/or carbon are added to a titanium alloy melt. These elements have complete solubility in the liquid but limited solubility in the solid. The solubility of boron in solid titanium is
