Microstructure and properties of Cu-Al-Ni-Mn-Y alloy with precipitation and effective strengthening by aging treatment

Abstract

The Cu-11Al-3Ni-2.5Mn-1Y alloy prepared by hot-press sintering was subjected to aging treatment at different temperatures of 350 °C, 400 °C, 450 °C, 500 °C and 550 °C, respectively. The phase composition, microstructure, mechanical and damping properties were characterized. The results show that the alloys after the ageing treatment are mainly composed of 18 R martensite and 2 H martensite. The precipitation phase begins to appear and the best comprehensive properties are obtained at the aging temperature of 450 °C. The hardness and strength values reached 347.6 HV and 642.6 MPa, respectively. The strengthening mechanisms are mainly involved in lattice distortion and dislocation increment effect caused by solution strengthening, shearing and hindering effect of precipitated phases and dislocations, fine grain strengthening effect caused by grain size reduction, and the increase of large angle grain boundary. Simultaneously, the room temperature damping reached 0.0723, which is 93 % higher than the original sample of 0.38. The improvement of damping properties is closely related to the changes in the number and size of martensite, the interfacial damping effect caused by precipitated phases, and the pinning and unpinning reaction between dislocations and precipitated phases. Therefore, alloys with both high mechanical and high damping properties can be obtained by proper aging treatment. In addition, the increase in phase transition temperature of high temperature damping properties also provides some guidance for the exploration and development of this alloy in the high temperature field.