Novel TiCuNiCo composites with high fracture strength and plasticity

摘要

Ti60Cu3oNi10_xCox (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 2480 MPa is achieved for Ti6oCU30Ni]0Co4 alloy com posite. The enhanced plasticity is attributed to the addition of Co element having a positive heat of mix ing 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 microstruc ture of the Ti60CU3oNi10Co4 alloy, i.e., the coexistence of amorphous phase, nanocrystals, and micron-scale dendrites.