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Talks and Poster Presentations (with Proceedings-Entry):

C. Poletti:
"Ti und Ti-Legierungen mit Teilchenverstärkung";
Talk: Materialica 2007, München; 10-17-2007 - 10-18-2007; in: "Materialica 2007. Light Metal", (2007), 27 pages.



English abstract:
The high specific stiffness and strength as well as the poor wear resistance of the titanium alloys can be improved by the addition of ceramic reinforcement. This work gives an overview of some powder-metallurgy processes to produce SiC reinforced titanium, of some microstructural features and mechanical properties of SiC, TiC and TiB reinforced titanium alloys and of hot forming processes, particularly forging. The production of a SiC reinforced titanium alloy using conventional powder metallurgy methods (PM) yields porosity and silicides formation. New PM processing methods will be shown: equal channel angular pressing (ECAP), Spark plasma sintering, sintering using an induction oven. Consolidation time and temperature are considerably decreased for hot extrusion avoiding the silicide formation, while consolidation loads were increased, in order to obtain a denser Ti-SiC composites. The wear resistance is compared between matrix and PRM. The problems that arrive from the production of SiC particulate reinforced titanium make other options more feasible. TiC and TiB particles can be added or grown in situ to increase the mechanical and tribological properties of titanium alloys. The compression strength and the Young´s modulus were measured up to 350°C for Ti662 alloy with 0vol%- 12vol%- 20vol%- TiC particles, Ti64 alloy unreinforced and reinforced with 12vol% TiC, 3vol% TiB, 15vol% SiC particles, and Ti Grade2 unreinforced and reinforced with 5vol%- 15vol% SiC particles. The hardness measurements at room temperature were used to understand the hardening mechanisms of the different ceramic particles. The hot formability is normally studied by compression tests, due to the their reproducibility and the constant strain rate obtained during the test. The processing maps have been used as a tool to identify the optimal forming parameters adjusting the flow data according to the dynamic mechanical model proposed by Prasad et. al. Here, the local deformation state was correlated with the local metallographic observations of Ti-6Al-6V-2Sn unreinforced, and reinforced with 12%vol of TiC particles and Ti-6Al-4V reinforced with TiB in-situ particles. The local microstructure was correlated with the generated local processing maps developed by Rao and Murty based on the Prasad et al model.

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