Influence of Sintering Temperature on the Microstructure and Mechanical Properties of In Situ Reinforced Titanium Composites by Inductive Hot Pressing

Abstract

This research is focused on the influence of processing temperature on titanium matrix composites reinforced through Ti, Al, and B4C reactions. In order to investigate the effect of Ti-Al based intermetallic compounds on the properties of the composites, aluminum powder was incorporated into the starting materials. In this way, in situ TixAly were expected to form as well as TiB and TiC. The specimens were fabricated by the powder metallurgy technique known as inductive hot pressing (iHP), using a temperature range between 900 °C and 1400 °C, at 40 MPa for 5 min. Raising the inductive hot pressing temperature may affect the microstructure and properties of the composites. Consequently, the variations of the reinforcing phases were investigated. X-ray diffraction, microstructural analysis, and mechanical properties (Young’s modulus and hardness) of the specimens were carried out to evaluate and determine the significant influence of the processing temperature on the behavior of the composites.

Study of the Influence of TiB Content and Temperature in the Properties of In Situ Titanium Matrix Composites

“…As it might be expected, precipitates are observed in the microstructure of the specimens, since at this temperature (1100 • C) there have been reactions between the matrix and the boron particles [10,32]. As many authors have previously described, these precipitates are supposed to be in situ formed TiB [28,33] because of this reaction (see Figure 2). It is important to highlight a clear evolution of the size and the volume of the precipitates related to the amorphous B content (vol %).…”

“…The powder mixture was dried and subsequently blended a second time for several minutes without the ceramic balls, to avoid possible agglomerations. This was the same blending procedure used for producing composites as in previous authors' works [28,30]. Then, the target composition of three different powder mixtures was made from titanium and 0.9, 2.5 and 5 vol % of B particles.…”

“…In case of the specimen fabricated by dHP, the operational conditions were similar than the iHP ones; however, only an operational temperature of 1000 • C was set. This value was fixed according to a previous authors' work in which an interesting microstructure phenomenon took place at this temperature in TMCs at similar conditions, but made from different raw materials [28].…”

“…In case of the specimen fabricated by dHP, the operational conditions were similar than the iHP ones; however, only an operational temperature of 1000 °C was set. This value was fixed according to a previous authors' work in which an interesting microstructure phenomenon took place at this temperature in TMCs at similar conditions, but made from different raw materials [28]. Once the iHP and dHP cycles were finished, the samples with 20 and 80 mm of diameter were taken out from the respective dies and cleaned by a sand blasting machine to remove the graphite paper remains from the surfaces.…”

“…In particular, inductive hot pressing (iHP) technology is valued for in situ TMCs manufacturing due to its short operational time (high heating rate ≤100 • C/min) [24][25][26]. The use of this technique has facilitated the investigation of TMCs' properties and the secondary phases formed at different processing temperatures [27,28]. Despite the advantages of this process, the restrictions of the specimens' size (diameters of 20 mm) limit the measurement of tensile and bending properties of the final specimens.…”