Abstract
The purpose of this study was to explore binary and ternary Cu-based bulk metallic glasses (BMG), which were divided into three systems: Cu-Hf-Al, Cu-Y-(M), Cu-Ti-M alloys, where M is an additive element. First, high Cu-content binary Cu-Hf BMG modified with Al, (Cu65Hf35)100-xAlx (x= 1, 2, 3, 4, 6) were studied. With only x= 2, the glass-forming ability (GFA) is greatly improved to form bulk glassy rod up to at least 3 mm in diameter. The microstructure consists of inhomogeneous amorphous phases. The Cu-Y binary system was chosen to study the GFA on compositions around the eutectic points and their modification. The microstructure of as-cast Cu-Y rods contained amorphous and crystalline mixture phases. According to the XRD results the best glass forming alloy is Cu78Y22. The further addition of Ag improves the GFA. The composition (Cu78Y22)97Ag3 was very close to form fully 1 mm BMG rod. Finally, we tried to develop the ternary BMGs based on high Cu content Cu-Ti BMG. The best result is the Cu50Ti40Zr10 glassy rod with the diameter at least 1 mm.The Cu-Y-M ternary alloys are brittle and poor electrochemical resistance due to their structure that contained amorphous and crystalline phases. Fully amorphous Cu-Hf-Al system showed the best mechanical properties with a compressive fracture strength up to 2340 MPa and a plastic strain up to about 1 % due to the inhomogeneous amorphous phases. Cu50Ti40Zr10 alloy performed low corrosion current density, 10-5 A/cm2, in 1 N H2SO4 + 0.01 N NaCl solution showed excellent electrochemical property, and its compressive fracture strength is up to about 2000 MPa.