Powder metallurgy: which of the following is <em>not</em> a standard industrial method for producing metal powders for sintering applications?

Introduction:
Powder production is the first critical step in powder metallurgy, controlling particle size, shape, purity, and flow—properties that directly affect compaction, sintering, and final part performance. Multiple mature technologies exist to generate metal powders at scale for ferrous and non-ferrous systems.

Given Data / Assumptions:

• Industrial relevance and scalability are central to the comparison.
• Powders must have controllable size distributions and minimal contamination.
• Common routes include melt disintegration, mechanical comminution, electrolytic, and chemical methods.

Concept / Approach:
Atomisation (gas, water, or centrifugal) is the workhorse for many alloys, producing irregular or near-spherical powders. Grinding/milling (ball, attritor, jet) is used for brittle materials or to refine powders. Electrolytic deposition yields high-purity, dendritic powders that are subsequently comminuted. Chemical reduction (e.g., of iron oxides with hydrogen/CO) produces sponge-like powders. 'Hammering' is not an industrial powder-making process; it is neither controlled nor efficient for producing suitable powder particles.

Step-by-Step Solution:
List proven powder production routes: atomisation, milling, electrolytic, chemical reduction.Evaluate 'hammering': lacks process control and scalability for powder manufacture.Identify it as the non-standard method.

Verification / Alternative check:
Powder metallurgy handbooks catalogue established processes and do not include hammering as a recognized method for industrial powder generation.

Why Other Options Are Wrong:

• Atomisation: Ubiquitous for steels, aluminum, and superalloys.
• Grinding/milling: Essential for brittle metals and intermetallics.
• Electrolytic deposition: Used for Cu, Ni, Fe with high purity.
• Chemical reduction: Foundational for iron powder production.

Common Pitfalls:
Assuming any mechanical impact process can make acceptable powders; shape, size control, and contamination matter greatly.

Final Answer:
hammering