Crystalline metal can be transformed into metallic glass by

Options

A. Alloying
B. Pressing into thin plates
C. Slow cooling of molten metal
D. Very rapid cooling of a spray of the molten metal

Answer

To solve the question "Crystalline metal can be transformed into metallic glass by...", we will analyze the options provided and determine the correct method for this transformation.

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Crystalline Metal**: A metal with a well-ordered structure where atoms are arranged in a repeating pattern.
- **Metallic Glass**: An amorphous metal that lacks a long-range ordered structure, often produced by rapid cooling of molten metal.

2. **Analyzing the Options**:
- **Option 1: Alloying**: This involves mixing different metals to create an alloy. While alloying can affect the properties of metals, it does not directly lead to the formation of metallic glass.
- **Option 2: Pressing into thin plate**: This refers to shaping the metal, but it does not change the crystalline structure into a glassy state.
- **Option 3: Slow cooling**: This method allows atoms to arrange themselves into a crystalline structure, which is the opposite of what we want for metallic glass.
- **Option 4: Very rapid cooling of spray of molten metal**: Rapid cooling prevents the atoms from arranging into a crystalline structure, leading to the formation of a metallic glass.

3. **Conclusion**:
- The correct answer is **Option 4: Very rapid cooling of spray of molten metal**. This method effectively transforms crystalline metal into metallic glass by preventing crystallization during the cooling process.

### Final Answer:
Crystalline metal can be transformed into metallic glass by **very rapid cooling of spray of molten metal**.