Compressive and wear behaviors of bulk nanostructured A12024 alloy

摘要

Compressive and wear properties of bulk nanostructured A12024 alloy prepared by mechanical milling and hot pressing methods were investigated. A12024 powders were subjected to high-energy milling for 30 h to produce nanostructured alloy. As-milled powders were compacted at 500℃ under 250 MPa in a uniaxial die. Consolidated sample had an average hardness and relative density values of 207.6 HV and 98%, respectively. Uniaxial compression tests at strain rates in the range of 1.67 × 10~(-4)-1.67 × 10~(-2) s~(-1) were performed using an Instron-type machine. The wear behavior of nanostructured sample was investigated using a pin-on-disk technique under an applied load of 20 N. The compression and wear experiments were also executed on samples of commercial coarse-grained A12024-0 (annealed) and A12024-T6 (artificially-aged) alloys, for comparison. The structure of consolidated A12024 was characterized by X-ray diffraction (XRD). The yield strength and compressive strength of nanostructured A12024 reached a value of ～698 MPa and ～712 MPa at strain rate of 1.67 × 10~(-4) s~(-1) respectively, which was considerably higher than those for coarse-grained A12024-O and A12024-T6 counterparts. Worn surfaces and the wear debris were analyzed by scanning electron microscopy (SEM), energy dispersive spec-troscopy (EDS) and XRD. Nanostructured A12024 revealed a low friction coefficient of 0.3 and a wear rate of ～12 × 10~(-3)mg/m, which are significantly lower than those obtained for A12024-O and A12024-T6 alloys. This enhanced wear resistance was mainly caused by nanocrystalline structure with high hardness value. The dominating wear mechanism of nanostructured AI2024 appeared to be delamination mechanism.