Effect of calcium addition on the microstructure and compressive deformation behaviour of 7178 aluminium alloy

Aluminium 7178 alloys containing 1% calcium are used to study the effect of calcium addition on their microstructure and compressive deformation behaviour. The compressive deformation behaviour of aluminium alloy containing 1% calcium is studied at varying strain rates (10−2–10/s). The material is prepared using stir casting technique. The yield stress, flow stress and elastic limit are measured from the true stress–strain graph. The strain rate sensitivity and strain-hardening exponent was also determined for each material at different strain rates. Its microstructural characterization reveals that Ca particles act as grain refiners for primary base alloy and helps in improving the strength of the virgin alloy. An empirical relationship has been proposed to predict the flow curve of the alloys as a function of strain and strain rate.

Research highlights
► The microstructure of 7178 alloy can be modified and refined through Ca addition.
► The microstructural modification and refinement causes increase in elastic limit stress and flow stress of 7178 alloy due to Ca addition.
► Plastic strengthening coefficient and strain-hardening exponent of the Ca added alloy are considerably higher than for 7178 alloy without Ca addition.