What does "heat of fusion" refer to in the context of casting?

"Heat of fusion" refers to the energy required to transform a solid into a liquid at its melting point while maintaining a constant temperature. In the context of casting, understanding the heat of fusion is crucial for processes involving melting metals, as it determines how much energy is necessary to change the metal's state from solid to liquid without raising its temperature further.

For casting, the heat of fusion is significant because it affects melting times and the overall energy efficiency of the casting process. Properly managing the heat of fusion ensures that the liquid metal can be poured into molds to create desired shapes and structures.

The other options do not accurately describe the concept. The temperature at which a metal melts pertains to its melting point rather than the energy involved in transitioning states. The speed of solidification relates to how quickly the liquid cooling process occurs, and the weight of a metal in its liquid form does not have a direct connection to the concept of heat of fusion. Thus, the energy requirement during the phase change solidifies the understanding of heat of fusion in casting applications.