Deformation behaviour of ultra-fine-grained copper

Abstract Mechanical behaviour and structural changes, such as the evolution of grain and dislocation structures and the formation of slip lines and grain-boundary-sliding traces, of a submicron-grained (SMG) copper during room-temperature compression have been studied. It is suggested that the absorption of dislocations into grain boundaries (GBs) is due to the migration and sliding of some highly non-equilibrium GBs during the deformation process and is influenced by high level internal stresses. From this point of view, the unusual behaviour of SMG copper, in particular, the high yielding and flow stresses, the absence of strain hardening, high plasticity and low strain rate sensitivity, are explained. Analogies of the mechanical behaviour of SMG copper with mechanical properties of metallic materials at large plastic strains in stage IV are discussed.

[1]  R. C. Gifkins.  The Measurement of Grain-Boundary Sliding in Polycrystalline Specimens , 1973 .

[2]  C. Hamilton,et al.  A mechanism for deformation-enhanced grain growth in single phase materials , 1991 .

[3]  A. A. Nazarov,et al.  Microstructures and hardness of ultrafine-grained Ni3Al , 1993 .

[4]  R. Averback,et al.  Grain growth in nanocrystalline TiO2 and its relation to vickers hardness and fracture toughness , 1990 .

[5]  R. Valiev,et al.  Plastic deformation of alloys with submicron-grained structure , 1991 .

[6]  J. Weertman,et al.  Grain-size dependent hardening and softening of nanocrystalline Cu and Pd , 1992 .

[7]  M. Ashby.  The deformation of plastically non-homogeneous materials , 1970 .

[8]  J. Weertman,et al.  Mechanical behavior of nanocrystalline metals , 1992 .

[9]  T. Christman,et al.  Processing and consolidation of bulk nanocrystalline titanium-aluminide , 1991 .

[10]  T. Langdon,et al.  An investigation of intercrystalline and interphase boundary sliding in the superplastic Pb-62% Sn eutectic , 1979 .

[11]  R. Valiev,et al.  Grain Boundaries during Superplastic Deformation , 1979, April 16.

[12]  R. Birringer,et al.  Investigation of self-diffusion in nanocrystalline copper by NMR , 1991 .

[13]  R. Valiev,et al.  Grain boundary structure and properties under external influences , 1986 .

[14]  A. Rosen,et al.  On the validity of the hall-petch relationship in nanocrystalline materials , 1989 .

[15]  Jens Lothe John Price Hirth,et al.  Theory of Dislocations , 1968 .

[16]  R. Valiev,et al.  Incorporation model for the spreading of extrinsic grain boundary dislocations , 1990 .

[17]  J. Weertman,et al.  Microhardness of nanocrystalline palladium and copper produced by inert-gas condensation , 1989 .

[18]  C. Koch,et al.  The hall-petch relationship in nanocrystalline iron produced by ball milling , 1990 .

[19]  Jeffrey Wadsworth,et al.  Superplasticity—Recent advances and future directions , 1989 .

[20]  R. Valiev,et al.  An investigation of ductility and microstructural evolution in an Al−3% Mg alloy with submicron grain size , 1993 .

[21]  L. M. Skinner.  Electron microscopy of thin films , 1967 .

[22]  A. Mukherjee,et al.  Microstructural aspects of superplasticity , 1985 .

[23]  M. Zehetbauer,et al.  Cold work hardening in stages IV and V of F.C.C. metals—I. Experiments and interpretation , 1993 .

[24]  N. A. Gjostein.  Comment on: “investigation of relative interfacial free energies in 304 stainless steel by electron transmission and diffraction microscopy” , 1969 .

[25]  R. Valiev,et al.  On the structure, stress fields and energy of nonequilibrium grain boundaries , 1993 .

[26]  R. Valiev,et al.  The effect of heat treatment on the elastic and dissipative properties of copper with the submicrocrystalline structure , 1993 .

[27]  R. Valiev,et al.  On the quantitative evaluation of superplastic flow mechanisms , 1983 .

[28]  R. Valiev,et al.  The Hall-Petch relation in submicro-grained Al-1.5% Mg alloy , 1992 .

[29]  R. Valiev,et al.  Dilatometric analysis of aluminium alloy with submicrometre grained structure , 1992 .

[30]  A. A. Nazarov,et al.  Model for the prediction of the mechanical behaviour of nanocrystalline materials , 1993 .

[31]  Doris Kuhlmann-Wilsdorf,et al.  Theory of plastic deformation: - properties of low energy dislocation structures , 1989 .

[32]  W. Łojkowski.  On the spreading of grain boundary dislocations and its effect on grain boundary properties , 1991 .

[33]  B. Günther,et al.  Secondary recrystallization effects in nanostructured elemental metals , 1992 .