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I.

INTRODUCTION

T I T A N I U M alloy composites consolidated by conventional hot pressing techniques generally suffer from degraded properties as a result of brittle reaction products that form in the matrix/reinforcement interfaces during processing and/or service exposures. [~-4] Most approaches to reducing or eliminating the reaction have centered on the inclusion of diffusion barriers, [5,6] although techniques for reducing consolidation temperature or time would appear to be more desirable from a practical point of view. Studies of the latter approach have been reported for both foil [7] and powder Is] starting matrix materials, with reductions in interfacial reactions being more significant in the foil material ~71 than in the powder material, i8] Shock-wave consolidation of titanium and titanium alloy powders has been reported by others; [9,~~ however, the use of this technique for the production of titanium matrix composites has not been explored extensively. This approach to producing titanium/SiC composites offers the potential for minimal reaction product formation because of its highly localized and transient heating pattern. [~2] Heating of the powders is generally considered to be confined to particle surfaces when an optimum velocity shock wave has been generated to consolidate the compact. ~2,~3] Shock-wave velocities typically achieved during consolidation are in the range of kilometers per second, resulting in consolidation times on the order of a microsecond. Whether the powder particle surface melts or is just heated to allow plastic deformation sufficient to bond to other particles is dependent upon several factors that can be controlled experimentally. The latter condition is the goal for consolidation of titanium matrix composites. In this work, experiments have been conducted to explore the viability of explosive shock-wave consolidation of gamma phase titanium aluminide powders blended with silicon carbide powders. The objective of this study is

to determine the extent of matrix/reinforcement interfacial interaction during consolidation. II.

EXPERIMENTAL

PROCEDURE

Titanium aluminide powder, produced by the Plasma Rotating Electrode Process with a composition of Ti-48 at. pct A1, consisted of particles ranging in size from less than 4 0 / x m to 300/xm. The silicon carbide powder was standard 1200 mesh (3/xm) abrasive compound. The titanium aluminide powder was mechanically blended into a mixture of 35 vol pct silicon carbide and sealed off under vacuum in a disc-shaped stainless steel container approximately 2 inches in diameter and 0.25 inches thick. The porosity of the sample was 15 pct. The experimental assembly was very similar to that described by DeCarli and Meyers.[14] Consolidation was effected by a shock wave generated from the detonation of a C-4 explosive charge which propelled a stainless steel flyer plate into the sample assembly. Flyer plate velocity was calculated to be 1.8 k m / s using the Gurney equation for grazing incidence, t14] The pressure in the sample is diff