Metal heat treatment and aluminium Flashcards
DMM1: Materials Deck 6
What is duraluminium?
a 4% copper aluminium alloy with higher yeild strength but simmilar density to pure aluminium
describe the intermetallic compond (theta) of a copper alumium alloy?
at 53% copper the metals chemically bond together forming a hard cermaic material
describe a grain boundary phase mixture
the main alloy phase forms metals crystals with the secondary phase forming between the grains
Describe a Lamellar Phase Mixtures
plate like particles of intermaetally compound with solid solution (usually pure metal) between them
What is a Eutectic mixture?
a very fine dispersion of phases where both phases are created from a liquid form at the same time
What is a hypoeutectic alloy?
a phase mixture where one phase solidifies before the other and the added metal is lower than a eutectic alloy
What is a hypereutectic alloy
a phase mixture where one phase solidifies before the other and the added metal is higher than a eutectic alloy
How does rapid cooling impact the phase systems created?
changes to a new phase are prevented and slowed
the metal is not in equalibrium and takes years to fully return to an equalibrium state giving it new properties
what is precipitation hardening
a hardening method which distributes the secondary phase more evenly throughout the alloy prevent dislocations moving and increasing hardness
What are the stages of precipitation hardening?
Stage 1 Solution treatment:
Hold at temperature at
which there is a single
solid-solution phase
Stage 2: Quenching
Rapidly cool forming Non-equilibrium supersaturated solid solution
Stage 3: Precipitation treatment
Hold at increased
temperature to allow
diffusion
System moves towards
equilibrium state releasing some of the internal stresses and hardness to allow for tougher material
