Microstructure evolution and mechanical properties for rapidly solidified Cu–3Ag-0.5Zr alloy during isothermal compression

Abstract

Rapidly solidified (RS) Cu–3Ag-0.5Zr alloy was prepared by hot isostatic pressing (HIP) and hot forging with rapid solidified alloy powder. Hot isothermal compressive deformation was conducted at room and elevated temperatures (400–900 °C) with a stable strain rate of 0.001/s. The mechanical properties and microstructure of alloy before compression and compression at different temperatures (400–900 °C) were investigated. The results show that the original Cu–3Ag-0.5Zr alloy has a 520 MPa compressive strength at room temperature, which is related to the small grain size (about 2 μm) of RS alloy and the interaction between second phases (Cu4AgZr, Ag particles) and dislocations. Compression at elevated temperatures (400–900 °C) will rise strength decreasing continuously and the compressive strength is just 23 MPa, specially Portevin Le-Chateliers (PLC) effect is observed after 700 °C, both of which results from the microstructure evolution of alloy at elevated temperatures. That the Ag particles will aggregate and grow up and dynamic recrystallization (DRX) is found at elevated temperatures. The two processes were both accelerated at higher temperature, which make the interaction between secondary phases and dislocations decreasing and finally the strength decreases. Portevin Le-Chateliers (PLC) effect is a result of intense interaction between DRX and plastic deformation. In addition, the discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) occur simultaneously during compression at elevated temperatures.