Crystal Plasticity Study Of Deformed Magnesium Alloys Containing Different Morphological Precipitation Phases

With the advantages of low density,high specific strength and good damping and shock absorption,magnesium alloys have wide application prospects in commercial passenger cars,aerospace,electronic devices and medical devices.However,magnesium alloys have disadvantages such as low strength and poor plastic forming ability,which seriously limit their large-scale applications.Precipitates strengthening is one of the effective methods to improve the strength of magnesium alloys.In magnesium alloys,different orientations,sizes,volume fractions,arrays and shapes（rod,plate and sphere）of the precipitates have different effects on the strength and plasticity of magnesium alloys.In this paper,the three-dimensional model of magnesium alloy containing different types of precipitates is established with pure magnesium as matrix and Mg₁₇Al₁₂ as precipitate by using crystal plasticity full-field model,and tensile loading is carried out along[2（?）（?）0]direction to systematically study the interaction between precipitates and magnesium matrix,and to obtain the influence law of deformation mechanism of different types of precipitates on magnesium alloy.The results show that the deformation mechanisms providing deformation for the magnesium alloy in tensile deformation are mainly prismatic slip,pyramidal<c+a>slip and compression twinning,and there are obvious strain incoherence and stress concentration near the precipitate,and the precipitation hardening effect of the magnesium alloy containing the precipitate is stronger than that of the magnesium alloy without the precipitate at the same plastic strain.For the volume fraction of 4%,the ratio of length,width and thickness is 10:3:1,the precipitation hardening effect of magnesium alloy containing parallel plate precipitate is the strongest when the angle between its habitual surface and basal surface is around 67.5°;the precipitation hardening effect of magnesium alloy containing non-parallel（60°distribution in the plane）plate precipitate is the strongest when the angle between its habitual surface and basal surface is around 90°.For the parallel plate precipitation phase parallel along the prismatic surface,the precipitation hardening effect of the magnesium alloy getting stronger continuously when the length increases from 6 to 40 units and the rest of the dimensions remain unchanged.For the rod-shaped precipitate with an axial length to diameter ratio of 10 and a volume fraction of 4%,the precipitation hardening effect of the magnesium alloy is strongest near an angle of 22.5°between the axial length direction and the c-axis of the magnesium matrix.When the axial length direction of the rod-shaped precipitate is along the c-axis direction,its axis length increases from 10 to 60 units,and the rest of the dimensions remain unchanged,the precipitation hardening effect of the magnesium alloy keeps getting stronger.In the case of constant size of spherical precipitate,the precipitation hardening effect of magnesium alloy keeps getting stronger with the increase of volume fraction of precipitate.