Solid - Solid Phase Transition Model

The easiest way for students to conceptualize the transition would be for the system to either release or absorb heat. I found a lesson plan created by the U.S. Department of Energy Pacific Northwest National Laboratory, which resulted in an exothermic reaction when held in one's hand. Using it as a reference for alloy composition (22% Al, 78% Zn), I tested and refined various fusion processes using a furnace until I developed a reliable system.

I also spent time developing a sand casting method that produced as smooth a product as possible. Because the phase transformation is initiated by transferring energy from your hand to the ingot, a smoother surface results in more surface contact and a more reliable phase change. It also minimized the amount of grinding and smoothing that was later required to prep the ingots.

The final product (pictured above before final separation and grinding) consistently performs a solid-solid phase transition. Because the phase transition releases heat, students can physically experience the transition, which aids in their conceptual understanding of a process that otherwise cannot be seen (to the naked eye).