TY - JOUR

T1 - Microstructure decomposition and unique mechanical properties in an ultrafine-grained Al-Zn alloy processed by high-pressure torsion

AU - Baris, A.

AU - Chinh, N. Q.

AU - Valiev, R. Z.

AU - Langdon, T. G.

PY - 2015/1/1

Y1 - 2015/1/1

N2 - An ultrafine-grained (UFG) Al-30wt.%Zn alloy was processed by high-pressure torsion (HPT) and then the mechanical and microstructural properties were investigated using depth-sensing indentations (DSI), focused ion beam (FIB), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Emphasis was placed on the microstructure changes due to HPT processing as well as the effects of grain boundaries and the unusually high strain rate sensitivity. The deformation characteristics are explained by the formation of a Zn-rich phase which wets the Al/Al grain boundaries and enhances the role of grain boundary sliding in this UFG alloy. The occurrence of intensive grain boundary sliding in this UFG alloy at room temperature was also demonstrated by deforming micro-pillars. It is shown that, as a result of grain boundary sliding, the plastic deformation process of the UFG samples remains stable even at the micro-scale without the intermittent flow and detrimental strain avalanches which are an inherent feature of micro-size conventional crystals. This result illustrates the advantage of using UFG materials for effective applications in micro-devices.

AB - An ultrafine-grained (UFG) Al-30wt.%Zn alloy was processed by high-pressure torsion (HPT) and then the mechanical and microstructural properties were investigated using depth-sensing indentations (DSI), focused ion beam (FIB), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Emphasis was placed on the microstructure changes due to HPT processing as well as the effects of grain boundaries and the unusually high strain rate sensitivity. The deformation characteristics are explained by the formation of a Zn-rich phase which wets the Al/Al grain boundaries and enhances the role of grain boundary sliding in this UFG alloy. The occurrence of intensive grain boundary sliding in this UFG alloy at room temperature was also demonstrated by deforming micro-pillars. It is shown that, as a result of grain boundary sliding, the plastic deformation process of the UFG samples remains stable even at the micro-scale without the intermittent flow and detrimental strain avalanches which are an inherent feature of micro-size conventional crystals. This result illustrates the advantage of using UFG materials for effective applications in micro-devices.

KW - Grain boundary sliding

KW - Indentation

KW - Micro-pillars

KW - Strain rate sensitivity

KW - Ultrafine grains

UR - http://www.scopus.com/inward/record.url?scp=84937211524&partnerID=8YFLogxK

U2 - 10.4149/km-2015-4-251

DO - 10.4149/km-2015-4-251

M3 - Article

AN - SCOPUS:84937211524

VL - 53

SP - 251

EP - 258

JO - Kovove Materialy

JF - Kovove Materialy

SN - 0023-432X

IS - 4

ER -