A piece of graphite cold iron does not act as fire, but mainly directly collides with the metal to produce the effect of phase change combustion. When the flame extracts the carbon again, the liquid metal and graphite will undergo eutectic, that is, when the graphite is extracted again, it is already a positively charged metal.

Why do you think the metal doesn't change color after cooling in the air? The rays emitted when electrons/electron transitions that could have been radiated are absorbed are the colors. Then it emits visible light when it encounters neutral substances such as oxygen. At this time, if you touch the metal with your hand, your body will heat up, and the friction will cause the metal to open the gaps between the carbon atoms that are not neatly arranged when the temperature rises, thus forming excess energy or chemical bonds, you It changed color.

(Student, I am revising the original answer now)--Student, you are still relatively simple children, thinking that it will be over after absorbing the external radiation. In fact, your thinking is not deep enough to go deep into the essence of carbon matrix, like the question asked. , wood, iron, and magnets are metals. The basic principle is that electrons rely on resonance, and when resonance reaches a certain frequency, there will be energy changes, and the trajectory of this energy change is the color. A typical example is the sound waves emitted when electrolyzing water metal wires. The metal wires are similar to another metal. The difference between the metal ball and the corresponding metal conductor with the corresponding resonant sound frequency is that the electrons on the metal ball have relative positions. On the iron, a trajectory of electrons can completely follow the resonance at the center of the sphere to produce a certain energy change.

(By the way, even if different grains in the same metal have different gaps, for example, the temperature between grains is different. In general, the crystal structure of metal grains is also very complicated. Clear, but we can imagine the combination of metal grains, and we can feel it.) Then the electronic resonance frequencies between different grains are also different, but because the metal structure is complex, there will be many resonance gaps, These gaps tend to emit light according to energy changes produced by resonant frequencies between the grains.

With regard to visual effects, during the resonance process of electronic waves between metals and certain liquids, the energy changes produced have little effect on visual effects. However, everything in the black area is black. When the concentration can be ignored, there is no color. For details, please refer to the picture:.