Powder Metallurgy and Reverse Engineering Practice Flashcards

Vocabulary flashcards covering key terms, processes, and analytical tools for Powder Metallurgy and Reverse Engineering as discussed in the lecture.

Powder Metallurgy

A manufacturing process that deals with metal or ceramic powders to produce parts, often characterized by high material utilization and suitability for complex, symmetric shapes.

Green Part

An unfinished part produced after the compaction step of powder metallurgy that possesses only enough strength for handling.

Green Strength

The mechanical strength of a compacted powder part before sintering, which is only sufficient for basic handling purposes.

Sintering

A thermal process heating a green compact to $70-90\%$ of its melting point to metallurgically bond particles through diffusion and increase part density.

Elemental Powder

Metal powders consisting of a single pure metal element, offering flexibility in mixing different alloys.

Prealloyed Powder

Powder particles where the proper proportion of ingredients is already present within each individual particle, resulting in a more uniform composition.

Solid State Reduction

A chemical process that removes oxides from material in a solid state to produce porous elemental sponge powders.

Gas Atomization

A production method where liquid metal is sprayed through a nozzle and cooled by high-speed inert gas or liquid to form spherical powders.

Aspect Ratio

The ratio of the largest dimension to the smallest dimension of a powder particle, with spherical particles having a ratio of $1$.

Shape Factor

The ratio of surface area to volume of a particle, where a higher ratio facilitates better diffusion during sintering.

Apparent Density

The original density of a powder, defined as the total mass divided by the total volume of the space it occupied.

Tap Density

The density achieved after a powder container is vibrated or tapped, causing particles to settle closer together.

Flowability

A characteristic of metal powders that influences how easily particles flow into a die during the compaction process.

Compressibility

The ease with which a powder can be compacted, which increases with the ductility of the metal particles.

Blending

The first step in powder metallurgy where elemental or prealloyed powders are mixed with lubricants and binders to create a uniform blend.

Compaction

The process of pressing powders into a die at high pressure to form a required shape through rearrangement and plastic deformation of particles.

Burnout

A step where compacted parts are heated to a moderate temperature to remove lubricants and binders added during the blending stage.

Necking

The initial non-densifying stage of sintering where atoms move along the interface to form a bond between particles, reducing surface area.

Internal Diffusion

A densifying sintering process where atoms from inside the particles are drawn toward each other, reducing gaps and increasing density.

Hot Isostatic Pressing (HIP)

An alternative method using hot gas to apply pressure from all directions, combining the pressing and sintering processes into one step.

Powder Injection Molding (PIM)

A manufacturing method using metal powders mixed with over $50\%$ polymer binder, which is melted to carry the powder into a die.

Reverse Engineering

The process of examining a product to understand its internal workings, manufacturing methods, and material properties.

Porosity

Voids or holes within a material microstructure that are characteristic of casting and powder metallurgy processes.

Fatigue

The most common failure mechanism where cracks grow incrementally under repeated stress until reaching a critical length, leading to catastrophic failure.

Phase Diagram

A thermodynamic map representing the phases of a material that exist at various temperatures and compositions under equilibrium conditions.

Solute Segregation

Also known as partitioning, this is the fluctuation in chemical composition throughout a microstructure caused by the solidification process.

Texture

The directionality or orientation in a microstructure, such as elongated grains, which serves as a telltale sign of deformation processes like rolling or forging.

Dendrites

Needle-like crystals that form as a metal freezes, which are a unique characteristic of cast or solidified microstructures.

X-ray Fluorescence (XRF)

A technology, often used in handheld guns, that determines material composition by measuring the characteristic x-rays emitted from atoms.