Q2. What is the effect of a SFE decrease on twinning?
The strong decrease in the twinning stress, observed when Mo is alloyed with Rh, has also been attributed to a SFE decrease [62].
Q3. How many twinning stresses were estimated for the normal stress?
Taking a value of 800 MPa for the normal stress, the slip-twinning transition was estimated for grain sizes of 3, 10, and 100 µm.
Q4. What is the effect of work hardening on the mechanical response of Cu?
The effect of work hardening can be incorporated into equation (21) by adding the term C2 n to the thermal component of stress; in FCC metals work hardening increases the density of forest dislocations, which constitute short-term barriers.
Q5. What is the effect of stress on the critical stress for twinning?
In general, the tendency for the occurrence of mechanical twinning in BCC and HCP metals [74– 76] is quite strong at high strain rates and low temperatures, because the flow stress can be effectively raised up to the level required for twin formation.
Q6. What is the effect of grain size on twinning?
It is seen that no twinning is obtained at 0.2, but that at plastic strain of 0.8 the twinning occurs for all strain rates, for the grain size of 10 µm.
Q7. What is the unique characteristic of twinning?
Another highly unique characteristic of twinning, first pointed out by Armstrong and Worthington [31], is the larger grain size dependence of the twinning stress, as compared with the slip stress.
Q8. What is the effect of solid solution atoms on the mechanical response of Cu?
The effect of solid solution atoms is manifested (both in the thermal and athermal components of stress) through the C2/3 relationship and the Labusch parameter L, which has different values for different solid solution atoms.
Q9. What is the possibility of twinning in near perfect HCP crystals?
The possibility of homogeneous nucleation of twins in near perfect HCP crystals was reported by Bell and Cahn [34] and Price [35].
Q10. What is the effect of interstitials on the tendency for twinning?
The rise in the twinning stress with interstitial content is more significant than the slip stress; this explains why the tendency for twinning decreases with interstitial increase.
Q11. Who was helpful in the development of the concepts presented in this paper?
Discussions with Professors R. W. Armstrong, G. Thomas and X. Markenscoff were most helpful in the development of the concepts presented in this paper.