Physical Properties Measurements, Inc.

Undercooling and recalescence of ZrSiO₄.
Frame rate = 2,900/second.

CO₂ laser beam melting of aluminum oxide (Al₂O₃).

This experiment illustrates laser beam melting of levitated aluminum oxide. Time interval = 0.5 seconds. Solid alumina remains at the bottom of the sample for 3.4 seconds. Stirring by the levitation gas flow increases when melting is complete.

Undercooling, solidification, and crystal phase transformation of Y₂O₃. Frame rate = 2,600/second.

Conclusions:

• The solid formed by crystallization is less dense than the liquid.
• A crystal phase transformation occurs at T > 2275 °C

Undercooled liquid Y₃Al₅O₁₂ (YAG) slow crystallization. Depending on sample size and cooling rate, liquid YAG may:

• Crystallize spontaneously with recalescence in less than 3 ms at an apparent temperature, T_A ≈ 1000 °C.
• Fail to crystallize and form a glass product.
• An unusual result was obtained in this experiment. The liquid cooled to T_A ≈ 880 °C, then crystallized slowly in a period of approximately 0.5 seconds.

Spontaneous nucleation of solid and rapid crystallization at deep undercooling.
Initial apparent temperature = 1550 °C

Crystallization at moderate undercooling initiated with an iridium "stinger"
Initial apparent temperature = 1790 °C

Crystallization at slight undercooling initiated with a sapphire "stinger"
Initial apparent temperature = 1925 °C