An increasingly important tool in modern experimental investigations is the ability to accurately produce a digital model or “digital twin” of samples and their properties. This goes hand-in-hand with the primary tenant of Industry 4.0 which is to provide advanced manufacturing solutions through the use of cyber-physical systems. A comparison of various quenching media, namely liquid nitrogen, water at 5 ℃, water at 20 ℃ and in the air on the microstructure of permanent mould cast AZ91 alloys was investigated. Particular emphasis was centred on the changes in microstructural features such as grain size and dendrite arm spacing. Phase-field method was used to produce a digital twin and qualitative analysis of the investigated cooling rates on AZ91. The combination of practical microstructural investigations and the simulated microstructures will advance the knowledge of cooling rate influences on AZ91 and their ability to be accurately simulated to assist with property and microstructural predictions.