Magnetic shape-memory alloys replace machines
Event details
| Date | 08.06.2012 |
| Hour | 11:00 |
| Speaker | Peter Müllner, Boise State University, Idaho |
| Location |
MXG312
|
| Category | Conferences - Seminars |
In the movie “Terminator 2” with Arnold Schwarzenegger as good guy T-800, Robert Patrick played the villain, a more modern T-1000 terminator. The T-1000 outperformed the T-800 because it was made of a liquid metal with the fabulous property of remembering shapes. The material replaced all the little machines which were built into the old T-800 terminator. Magnetic shape-memory alloys do exactly that: they enable the replacement of machines by materials and introduce a new paradigm for mechanical engineering, particularly useful for the miniaturization of mechanical devices. A pump no larger than 2 x 10 x 25 mm delivers tiny volumes at unprecedented speed and precision. This pump is an enabling technology of the lab-on-a-chip. The magnetic-field-driven migration of a cavity on a Ni-Mn-Ga single crystal rod transports the fluid. The cavity moves via the motion of twin boundaries at stresses well below 1 MPa. This very low twinning stress makes the material susceptible to internal and external constraints such as grain boundaries and clamping mechanisms. Clamping stresses generate cracks and trigger fracture upon dynamical loading. I will discuss twinning mechanisms from the atomistic to the macroscopic length scale with an emphasis on manipulating the twin microstructure via training and surface treatments. Ni-Mn-Ga alloys with optimized twin microstructures overcome internal and external constraints and perform consistently over extended life times.
Practical information
- General public
- Free
Organizer
- Boise State University, Boise, Idaho
Contact
- Boise State University, Boise, Idaho