Densification and compressive strength ofin-situ processed Ti/TiB composites by powder metallurgy

Abstract

In the present study, the densification of Ti/TiB composites, the growth behavior of in-situ formed TiB reinforcement, the effects of processing variables -such as reactant powder (TiB 2 , B 4 C), sintering temperature and time -on the microstructures and the mechanical properties of in-situ processed Ti/TiB composites have been investigated. Mixtures of TiB 2 or B 4 C powder with pure titanium powder were compacted and presintered at 700 o C for 1 hr followed by sintering at 900, 1000, 1100, 1200, and 1300 o C, respectively, for 3hrs. Some specimens were sintered at 1000 o C for various times in order to study the formation behavior of TiB reinforcement in-situ formed within the pure Ti matrix. TiB reinforcements were formed through different mechanisms, such as the formation of fine TiB and the formation of coarse TiB by Ostwald ripening or the coalescence of fine TiB. There was no crystallographic relationship between TiB reinforcement and the matrix. There were voids at the interface between the TiB reinforcement and the Ti matrix due to the preferential growth of coarse TiB without a particular crystallographic relationship with pure Ti matrix and the surface energy between the Ti matrix and TiB reinforcements. Therefore, the densification of Ti/TiB 2 compacts was hindered by the preferential growth of coarse TiB reinforcements. The mechanical properties of in-situ processed composites were evaluated by measuring the compressive yield strength at ambient and high temperatures. The compressive yield strength of the in-situ processed composites was higher than that of the Ti-6Al-4V alloy. It was also found that the compressive yield strength of the composite made from TiB 2 reactant powder was higher than that of the composite made from B 4 C at the same volume fraction of reinforcement. A crack path examination suggested that the bonding nature of interface between matrix and reinforcement made from TiB 2 reactant powder was better than that made from B 4 C.

Effect of Powder Particle Shape on the Properties of In Situ Ti–TiB Composite Materials Produced by Selective Laser Melting

“…This indicates the occurrence of a chemical reaction between CP-Ti and TiB2 powder during the SLM process, leading to the formation of Ti-TiB composite. This is similar to other studies, in which a chemical reaction between Ti and TiB2 during processing has been reported [13,15,16] . Fig.…”

“…Generally, conventional technologies such as casting [15] and powder metallurgy [16] are applied for in situ producing of Tibased composites but these methods are usually time-, energy-and material-consuming and it is not easy to fabricate complex-shape parts, which are highly needed in many fields specially biomedical industry. Emerging advanced technologies such as additive manufacturing techniques can not only produce 3D-shape components of high quality and complex features but also be capable of reducing production time as well as increasing primary material usage [17][18][19] .…”

Mechanical behavior of porous commercially pure Ti and Ti–TiB composite materials manufactured by selective laser melting

“…Previous studies used different compounds in order to reinforce Ti and these include TiN [12], TiC [13], SiC [14], B 4 C [15] and TiB [16]. As shown in Refs.…”

Mechanical Behavior and Microstructure Evolution of a Ti-15Mo/TiB Titanium–Matrix Composite during Hot Deformation

“…The latter was obtained through the addition of 15 wt.% of Mo into Ti. The composite produced by SPS showed a very attractive combination of strength and ductility (1.5-2 GPa and~22%, respectively) ( Figure 3a) at room temperature, which is superior to most of the β-rich alloys in the heat-strengthened condition [22] or metal-matrix composites with the hcp α-Ti matrix [4,23,24]. The observed increase in ductility is obviously associated with a greater number of slip systems in the bcc lattice in comparison with that of the hcp one [25].…”