Overcoming the strength-ductility trade-off in additively manufactured AlSi10Mg alloy by ECAP processing

Abstract

To overcome the trade-off between strength and ductility of the additively manufactured AlSi10Mg alloy used in the automotive and aerospace industries, samples with multilevel structural heterogeneities were produced using single-pass ECAP at 150 degrees C and 200 degrees C. The microstructures of these samples were composed of partially ruptured Al/Si cellular networks and alternatively arranged zones of elongated (pancaked) grains separated by wide zones composed of ultrafine grains. Experimental results demonstrated that AlSi10Mg deformed at 150 degrees C, exhibited a superior ultimate tensile strength (UTS) of ~541 MPa, but limited ductility. The sample deformed at 200 degrees C exhibited both high ultimate tensile strength (UTS ~463 MPa) and excellent elongation at break of ~16.3%. Those results revealed a superior combination of strength and ductility that originated from bimodal grain size distribution, Orowan bowing, mechanical twinning of the hard Si phase, and back-stress hardening. Our results shed new light on the unexploited potential in improving the mechanical properties of additively manufactured alloys.