So, you want to do a “Magic Show!” Student Presenter Packet for y-chem Outreach Program (10/11/2014)
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Memory Wire (U to Y)Memory wire is bent into a letter “U” or any desired shape. When placed in boiling water or suspended above steam, the wire snaps to the letter “Y” to represent BYU. Set UpShape the memory wire into the “U” (using the mold, with the wire welds at the bottom of the U to prevent the wire from springing out of the water as it changes shape) or into any desired shape. Boil 2-3 inches of water on a hot plate. Place memory wire next to hot plate with tweezers. SafetyBe careful with boiling water. Clean-up/DisposalRemove the wire from the water, and pour out the water. Re-form the memory wire to the U shape and store it with the mold. ChemistryMemory wire is a patented Nickel-Titanium alloy called NiTinol. NiTinol memory metal has two crystalline phase forms with a transition temperature between 30º and 50º C. Below the transition temperature, the memory wire is in a solid phase that is flexible, called the Martensite phase. Above the transition temperature, the NiTi alloy prefers the Austenite phase which is characterized by its rigidity. The memory wire alloy crystal consists of tiny planar areas called crystallites. Several metal atoms are bound together as one small cluster of metal atoms. When the wire is bent below the transition temperature, the bonds between the crystallites flex slightly. 
When the alloy is heated into the Austenite phase, the planes are slid back into place and the structure reverts to its original form. The Martensite structure has 24 different variants to carry out this transformation and, as a result, can be deformed in nearly any direction. Thus, the metal appears to 'remember' its original shape. However, if the wire is bent at a temperature above 500 °C, the crystallites reorient to take on a new shape. 
This new shape can also be bent at temperatures below the transition phase. 
As the wire is heated to the Austenite phase, the wire will remember this new set shape. Presentation“U to the Y”: Drop the “U” shaped piece of memory wire into the boiling water. It will immediately re-form into the “Y.” Pull out with tweezers and present to the class. The experiment does not work well at temperatures below 80 °C. The punchline of the demonstration is “when the heat is on, the Y will always come out on top” or something similar. If a slower reaction is desired, suspend the “U” above the steam with a ring stand. It takes approximately 5 minutes for U to slowly morph to the Y. Directory: wp-content -> uploads -> 2014 2014 -> For want of a nail 2014 -> Stop Militarizing Law Enforcement Act of 2014 2014 -> Ihbb asian Championships 2014 middle school bowl Round 4 First Quarter 2014 -> Ihbb european Championships 2014 Bowl Round 4 First Quarter 2014 -> International History Bee and Bowl 2013-14 Asian Division Question Set Bowl Round Six 2014 -> United states patent and trademark office 2014 -> Coffs harbour eisteddfod vocal syllabus 2014 -> Listen News Programs Schedule pledge now 2014 -> Slow club announce third album complete surrender Download 177.95 Kb. Share with your friends:
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