Novel TiCuNiCo composites with high fracture strength and plasticity

Ti₆₀Cu₃₀Ni_10-xCo_x (x=0, 2, and 4) alloys with high fracture strength and large compressive plasticity have been investigated. The microstructure and fracture morphologies have been studied by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The largest compressive fracture plastic strain of 32.5% with the fracture strength of 2480MPa is achieved for Ti₆₀Cu₃₀Ni₁₀Co₄ alloy composite. The enhanced plasticity is attributed to the addition of Co element having a positive heat of mixing with Cu element, and the retardment for the shear band propagation resulted from the dendrites, which are homogeneously distributed in the matrix. The high fracture strength of the alloys is resulted from work hardening character due to a series of dislocations in the dendrites and the unique microstructure of the Ti₆₀Cu₃₀Ni₁₀Co₄ alloy, i.e., the coexistence of amorphous phase, nanocrystals, and micron-scale dendrites.