Effects of Cu Content on Microstructures and Mechanical Properties of Ti-Ni-Based Amorphous Composites

Ti-Ni-based amorphous composite samples (Ti0.5Ni0.5)100-xCux with different Cu contents but the same diameter which has been prepared by the copper mold suction casting. The effect of the Cu contents (x=0, 10, 15, 20, 25, 30, 35, 40, at%) on the microstructures and mechanical properties of the amorphous composites was studied. Results show that both fracture strength and plastic strain of the alloy are very high when the copper content is x=20. Meanwhile the alloy exhibits the best comprehensive properties. As the x value increases, the glass forming ability of (Ti0.5Ni0.5)100-xCux alloy shows a waveform change from increasing to decreasing and then to increasing, but following an overall trend towards decreasing. The plasticity of Ti-Ni-based amorphous materials can be improved by adding Cu element in modest quantities (x≈25) to the Ti-Ni-based composites; however, adding more Cu (i.e., x>30) neither can improve the amorphous forming ability nor can enhance its strength. When x=15, the alloy has the highest breaking strength of 2440 MPa while gets the higher yield strength of 1471 MPa causing 17.15% plastic strain. The data are pretty high with respect to other amorphous systems or other alloy systems with memory of their shapes. When x=25, there is a certain increase in the alloy plastic strain with 21.35% plastic deformation.