Temperature dependence of dislocation mobility in Ni{sub 3}Al
- Michigan Technological Univ., Houghton, MI (United States). Dept. of Physics
The stress and temperature dependence of the dislocation velocity v({sigma}, T) has been studied experimentally in Ni{sub 3}Al single crystals. The mobility of individual dislocations was measured by the stress pulse-etching technique at temperatures between 77 and 873 K at the resolved shear stresses between 25 and 150 MPa over a range of dislocation velocities from 3 {times} 10{sup {minus}7} to 3 {times} 10{sup {minus}5} m/s. Fresh dislocations were introduced and revealed by a selective etchant on {l_brace}001{r_brace} surfaces of electropolished specimens annealed at 1,473 K for 120 hours in argon. The specimens were deformed in three point bending around {l_angle}110{r_angle} bending axis at a constant temperature. The dislocation arrays moved in two acting {l_angle}110{r_angle}{l_brace}111{r_brace} primary glide systems. The motion occurred over a range of applied stresses close to the microscopical yield stresses {sigma}{sub y}. The dislocation velocity decreased as temperature increased, in perfect analogy to the experimental data on {sigma}{sub y} obtained before on the same Ni{sub 3}Al. No detectable violation of the Schmid law was observed. The stress dependence of the dislocation velocity was rather steep resulting in a relatively large activation area of A = 100--200b. Such an activation area is greater than that one could expect in a kink-mode crystal with predominant Peierls mechanism for dislocation motion, although it is considerably less than A measured in other materials controlled by local obstacles.
- OSTI ID:
- 72464
- Report Number(s):
- CONF-941144--; ISBN 1-55899-265-0
- Country of Publication:
- United States
- Language:
- English
Similar Records
{l_angle}100{r_angle} Burgers vector in single phase {gamma}{prime} material verified by image simulation
In situ straining experiments on Fe{sub 70}Al{sub 30} single crystals