Significance of stacking fault energy on microstructural evolution in Cu and Cu-Al alloys processed by high-pressure torsion

• Published in: Philosophical magazine (Abingdon, England) Vol. 91; no. 25; pp. 3307 - 3326
• Main Authors: An, X.H., Lin, Q.Y., Wu, S.D., Zhang, Z.F., Figueiredo, R.B., Gao, N., Langdon, T.G.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Group 01.09.2011; Taylor & Francis
• Subjects: Alloys; Condensed matter: structure, mechanical and thermal properties; copper; COPPER ALLOYS (40 TO 99.3 CU); Copper base alloys; Cu-Al alloys; Defects and impurities in crystals; microstructure; Deformation and plasticity (including yield, ductility, and superplasticity); Evolution; Exact sciences and technology; HARDNESS; HIGH PRESSURE; high-pressure torsion; Homogeneity; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Microhardness; Microstructure; MICROSTRUCTURES; Physics; STACKING FAULT ENERGY; STACKING FAULTS; Stacking faults and other planar or extended defects; Structure of solids and liquids; crystallography; Torsion; Grain size; Temperature dependence; Crystal twin; Crystal defects; Stacking faults; Mechanical properties; Microhardness; Fragmentation; Quantity ratio; Aluminium alloys; High pressure torsion; Copper alloys; Microstructure; Recovery (properties)
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786435.2011.577757

Disks of pure Cu and several Cu-Al alloys were processed by high-pressure torsion (HPT) at room temperature through different numbers of turns to systematically investigate the influence of the stacking fault energy (SFE) on the evolution of microstructural homogeneity. The results show there is initially an inhomogeneous microhardness distribution but this inhomogneity decreases with increasing numbers of turns and the saturation microhardness increases with increasing Al concentration. Uniform microstructures are more readily achieved in materials with high or low SFE than in materials with medium SFE, because there are different mechanisms governing the microstructural evolution. Specifically, recovery processes are dominant in high or medium SFE materials, whereas twin fragmentation is dominant in materials having low SFE. The limiting minimum grain size (d min ) of metals processed by HPT decreases with decreasing SFE and there is additional evidence suggesting that the dependence of d min on the SFE decreases when the severity of the external loading conditions is increased.