D03+hcp mixed phase with nanostructures in Mg85Zn6Y9 alloy obtained by high-pressure and high-temperature treatments

• High pressure and high temperature treatment realized Mg85Zn6Y9 alloy.
• A pressure–temperature phase diagram of Mg85Zn6Y9 alloy is given.
• Phase separation from LPSO in Mg85Zn6Y9 alloy to D03 and hcp structure occurs.
• A stripe-patterned nanostructure consisting of D03 and hcp is formed.

High pressure and high temperature state of long period stacking order structure (LPSO) synchronized with chemical concentration in Mg85Zn6Y9 alloy have been investigated. A stripe-patterned nanostructure consisting of D03 and hcp phases is formed in Mg85Zn6Y9 alloy by high pressure and high temperature treatments. The nanostripe patterns are created by the phase separation of LPSO synchronized with chemical concentration. A pressure–temperature phase diagram is given in this research. LPSO is stable below 673 K, the D03+hcp mixed phase dominant above 973 K under the pressure up to 20 GPa. Phase separation under high pressure is useful for the fabrication of nanostructured metallic materials.