Microstructure of Ti-based, dendrite/nanostructured-matrix composites

Electron microscopy of the composite-forming alloys Ti₆₀Cu ₁₄Ni₁₂Sn₄Nb₁₀ and Ti ₆₀Cu₁₄Ni₁₂Sn₄Ta₁₀, shows that for both alloys, the microstructure consists of an array of micron-scale dendrites surrounded by a nanoscale binary eutectic. In the Ta-containing alloy, one of the eutectic phases has been identified as having a bcc crystal structure similar to that of the dendrites. In the Nb-containing alloy, one of the eutectic phases has been found to have a similar composition to that of the dendrites. Further detailed structural and compositional characterization is needed in order to understand the solidification behaviour of such materials. This knowledge may then be used to improve the casting conditions and subsequent mechanical properties of the materials.