Application of simple practical models for early stage ageing precipitation kinetics and hardening in aluminium and magnesium composites

In this paper, precipitation and hardening kinetics in the early stage of ageing of several aluminium and magnesium composites is modelled, based on well-known physical metallurgical theories. Both natural and artificial ageing is considered. Johnson–Mehl–Avrami approach is used, coupled with precipitation strengthening mechanism and theory. The work has demonstrated the feasibility of extending the established metallurgical theory to quantifying precipitation and hardening kinetics of composite materials based on relatively simple experimentation and calculation methods. As such, the methods are not academically sophisticated but are especially suitable for applications in the heat treatment practice of aluminium and magnesium composites when the precipitation process needs to be controlled by varying time and temperature for targeted properties. Precipitate phase identification and microscopy are not involved in deriving the relationship between hardness and ageing time.