Hot pressing of plasma-sprayed SiC fiber-reinforced Ti-6Al-4V alloy

Advanced titanium alloy metal matrix composites offer significant mechanical improvements over many conventional materials. In order to minimize fiber-matrix chemical reactions due to high temperatures involved in the fabrication methods, the final component can be obtained using two different steps: (1) fabrication of preforms (monotapes) by inert plasma spraying and (2) hot pressing of the fabricated preforms. Continuous SiC fiber-reinforced Ti-6Al-4V preforms were hot pressed to fabricate a composite multilayer. Different values of hot pressing processing parameters (temperature, applied load, bonding time) were investigated on the basis of a two-level factorial design. Metallographic and scanning electron microscopy (SEM) analyses were carried out to evaluate the bonding degree of the fabricated preforms. Preliminary three-point bending tests were also performed to understand the mechanical behavior and to show the more suitable values of the processing parameters for a hot pressing procedure. These values should be in the range of 830 to 950 degrees C (temperature), 80 MPa (applied stress), 20 to 30 min bonding time to avoid undesired phase transformation, large plastic flow of the metal matrix, and detrimental chemical reaction at fiber-matrix interface.