Kinetics of flow stress in crystals with high intrinsic lattice friction

A relatively simple theoretical model, based on the concept of kink-pair mode of escape of screw dislocations trapped in Peierls valleys, has been developed to account for the observed temperature dependence of the critical resolved shear stress (CRSS), τ, and of the associated activation volume, v, in crystals with high intrinsic lattice friction at rather low temperatures. In this model, the CRSS varies with temperature T as τ1/2 = A–BT, and the associated activation volume v depends on temperature T as v −1 = C–DT, where A, B, C and D are positive constants. Moreover, the activation volume v is found to be a function of τ such that vτ1/2 is constant for a given slip system. Data analysis of the temperature dependence of the CRSS of W, α-Fe, Cr and V metal crystals shows excellent agreement between theory and experiment in both regime III (low temperature or high stress) and regime II (intermediate temperature/stress). However, the predicted temperature and stress dependence of the activation volume are borne out by experiment in regime II, but lack quantitative agreement in regime III. On the other hand, the CRSS of CdTe crystals at low temperatures (T ≤ 200 K) is determined by the Peierls mechanism, whereas the weak temperature dependence of the CRSS above 200 K is probably governed by the breakaway of edge dislocation segments from arrays of pinning points due to localized defects in the crystal.

[1]  D. Brunner.  Comparison of Flow-Stress Measurements on High-Purity Tungsten Single Crystals with the Kink-Pair Theory , 2000 .

[2]  Toshio Suzuki,et al.  Plastic homology of bcc metals , 1999 .

[3]  Alfonso H.W. Ngan,et al.  A new model for dislocation kink-pair activation at low temperatures based on the Peierls-Nabarro concept , 1999 .

[4]  Toshio Suzuki,et al.  Plastic anisotropy in b.c.c. transition metals , 1997 .

[5]  A. Seeger,et al.  The Flow Stress of Ultra‐High‐Purity Molybdenum Single Crystals , 1997 .

[6]  S. Takeuchi,et al.  Motion of a screw dislocation in a two-dimensional Peierls potential , 1997 .

[7]  Takayoshi Suzuki,et al.  Plastic flow stress of b.c.c. transition metals and the Peierls potential , 1995 .

[8]  M. Z. Butt,et al.  Investigation of the activation parameters of low-temperature slip in anthracene single crystals , 1993 .

[9]  M. Z. Butt,et al.  Solid-solution hardening , 1973, Journal of Materials Science.

[10]  D. Brunner,et al.  Temperature and Strain-Rate Dependence of the Tensile Flow Stress of High-Purity α-Iron below 250 K II. Stress/Temperature Regime II and Its Transitions to Regimes I and III† , 1991 .

[11]  D. Brunner,et al.  Temperature and Strain‐Rate Dependence of the Tensile Flow Stress of High‐Purity α‐Iron below 250 K. I. Stress/Temperature Regime III , 1991 .

[12]  D. Brunner,et al.  Strain‐Rate and Temperature Dependence of the Tensile Flow Stress of High‐Purity α‐Iron above 250 K (Regime I) Studied by Means of Stress‐Relaxation Tests , 1991 .

[13]  M. Z. Butt.  Stress equivalence of solid-solution hardening , 1990 .

[14]  K. Kojima,et al.  Low-temperature deformation in anthracene crystals , 1990 .

[15]  S. Takeuchi,et al.  Deformation mechanism and photoplastic effects in CuBr single crystals , 1988 .

[16]  D. Brunner,et al.  The use of stress‐relaxation measurements for investigations on the flow stress of α‐iron , 1987 .

[17]  M. Werner.  Temperature and strain‐rate dependence of the flow stress of ultrapure tantalum single crystals , 1987 .

[18]  H. Mughrabi,et al.  Temperature- and strain-rate dependence of the flow stress of ultrapure niobium single crystals in cyclic deformation , 1983 .

[19]  S. Takeuchi,et al.  Slip in high purity tantalum between 0.7 and 40 K , 1977 .

[20]  J. Diehl,et al.  On the characteristic features of solution softening and hardening in B.C.C. metals , 1976 .

[21]  C. T. Wang,et al.  The deformation mechanism for high-purity , 1972 .

[22]  Taiji Suzuki,et al.  Orientation dependence of slip in tantalum single crystals , 1972 .

[23]  G. Taylor.  Comments on the paper `The flow stress of body-centred cubic metals at low temperatures' , 1969 .

[24]  P. Feltham.  The flow stress of body-centred cubic metals at low temperatures , 1969 .

[25]  R. Arsenault.  The double-kink model for low-temperature deformation of B.C.C. metals and solid solutions , 1967 .

[26]  J. Friedel.  CHAPTER V – DISLOCATION CLIMB , 1964 .

[27]  H. A. Lipsitt,et al.  The plastic deformation of chromium at low temperatures , 1962 .