Alloys

Useful information
Kit List: 

Alloy Model
Cutlery, cheap stainless set more expensive stainless set (all spoons)
Magnet
Shape memory springs
Normal steel spring
Kettle or at least access to one
Glass mug
Other lumps of metal could be good needs more thought
Nitol Magic Tricks (Bending Paperclip and Heart Wire)

Packing Away: 

This experiment now lives in the new small blue box called 'Periodic Table, Alloys and Carbon Allotropes', all three experiments may be done in combination. It's contained in a small Tupperware and a pencil case.
This experiment used to live in Misc box.

Frequency of use: 
1
Explanation
Explanation: 

EDIT: I (Yaron) am on tour at the moment but when I get back I will be working on a major overhaul for this experiment. Firstly, we'll be using cigarette lighters to heat the Nitinol because it's just so much more convenient than a kettle with water.

"But Yaron", I hear you say. "Won't the metal oxidise?" As Stephen Hawking used to say, "yes, probably." But we can replace it all when it stops working. We have loads of Nitinol, it can't be that expensive.

Also, I really want to take all the knives and forks out of the experiment since a kid threatened to STAB ME earlier. And we should replace the spoons with less rusty ones because it's difficult to demonstrate that stainless steel is oxidation resistant when all your SS samples have rusted.

Finally, we should get a couple more samples to talk about because the demonstration is a little short. Perhaps an Al-Cu alloy to talk about age hardening? Can anyone convince the materials department to donate a single crystal turbine blade?

OLD RA:

What is an alloy? A metallic, which is a metal mixed with something. More rigorously: A metallic solid or liquid that is composed of a homogeneous mixture of two or more metals, or of metals and nonmetal or metalloid elements, usually for the purpose of imparting or increasing specific characteristics or properties.

Say that you can tell how expensive someone's cutlery is from whether it is magnetic. Good stainless steel contains Cr and Ni, the Ni stabilizes austenite phase which is not magnetic. Bad stainless steel contains just Cr, this means the ferrite (magnetic) phase is stable and therefore cheap cutlery is magnetic. The proportions are usually 18:10, 18:8 or 18:0 Cr:Ni - the higher the Ni content the higher the quality. Show that the good John Lewis stainless steel is non-magnetic and the cheap Asda stainless steel is magnetic. The result of this means the Asda cutlery marks more easily.

(Look at other properties. Ask if they know the difference between hardness and toughness? Most won't, toughness is a measure of the amount of energy it can take before fracturing, whereas hardness is a measure of its how hard it is to permanently deform. Have two bits of metal, one martensite, one pearlite phase. Show that martensite can scratch the pearlite but not vice versa. Then try to bend the samples, can easily bend pearlite, martensite would just fracture.)

*Care necessary here, if springs are stretched too far then they won't reversibly return to the correct length.*

Finally, shape memory alloys. Allow them to slightly deform the normal and shape memory spring. Ask them what they think would happen if it was put in warm water. Put it in water straight out the kettle. One will return to original shape, normal spring won't. Explain that when load applied layers slide out, then when heated it shifts to the austenite phase before crinkling to matensite when cooled. See diagrams in box.

Risk Assessment
Date risk assesment last checked: 
Thu, 13/12/2018
Risk assesment checked by: 
Tdwebster
Date risk assesment double checked: 
Sun, 04/02/2018
Risk assesment double-checked by: 
Giedre
Risk Assessment: 

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Hazard Risk Likelihood Severity Overall Mitigation Likelihood Severity Overall
Heat gun Fire risk and also the possibility of burns. 3 3 9 Demonstrator to control heat gun. Do not leave on. Keep flammable material away from the heat gun. Use stand instead of lying heat gun on a surface. Do not touch the heat gun.
In case of burns, run affected area under cold tap for 10 minutes. Call a first aider. Follow venue RA protocols in case of fire.
2 3 6
Hot water Scalds 2 3 6 Use only a little water at bottom of mug, heat only when needed. Run under cold tap for 10 mins. 2 2 4
Cuterly Stabbing self/others 4 3 12 Use relatively blunt cutlery, no properly sharp knifes. Preferably only spoons. 4 1 4
Magnets Skin getting caught between cutlery and magnet 3 3 9 Use weak magnet so won’t cause harm if occurs 3 1 3
Atomic Structure Model Potential splinters from wood/sharp ends of wire in atomic structure model. 3 2 6 Atomic structure model has wood sanded/wire ends protected/ends not exposed. 3 1 3
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