Research :: Composites

Ti-6Al-4V/TiC Metal Matrix Composites:

Metal matrix composites have the potential for significantly higher strength and more ductility than their monolithic counterparts.  In ballistic applications, for which this composite system was considered, the composite must show high strength, reasonable ductility, and good abrasion resistance.  This study was an investigation of  the deformation and failure mechanisms of Ti-6Al-4V/TiC particulate and layered composites at quasi-static (10^-1 - 10¹ s^-1) and high strain rates (10³ s^-1).

Particulate Composites:

• 25% increase in strength observed for just 1% vol TiC (Figure 1))
• Typical strengthening mechanisms for MMCs not important for Ti64/TiC system
• Include matrix strengthening by grain size/subgrain size refinement, work hardening matrix during processing, elastic thermal mismatch stresses (determined by Eshelby)
• Load transfer (Eshelby) from particle to matrix not significant
• C in solution dominant mechanism, independent of vol fraction TiC

Layered Composites:  

• Sandwich structure, diffusion bonded particulate composite (10%TiC) and monolithic Ti64 (Figure 1). 
• Processing eliminates interface resulting in continuous matrix (Figure 2).
• Outer particulate layer provides strength and abrasion resistance,  inner monolithic layer provides ductility to the structure. 
• Crack arrested and deflected at interface!  (Figure 3).

Figure1	Figure 2	Figure 3

This work was supported primarily by the National Science Foundation sponsored Materials Research Science and Engineering Center, Contract No. DMR-0079964, at Brown University. AWJ was also sponsored by a GANN Fellowship and ASSERT award while conducting the research.

Research :: Composites