AZ91 alloy, the most widely used Mg casting alloy, exhibits low strength/ductility and weak energy absorption, which is a function of its large grain size and the presence of a coarse and continuous network of β-Mg₁₇Al₁₂ intermetallic compounds. This work demonstrated that friction stir processing (FSP) enables enhancement of strength and energy absorption capability of AZ91 alloy. The influence of FSP treatment on various potential strengthening mechanisms, including grain boundary, solid solution, and sub-micron particle strengthening mechanisms, was studied. It is identified that the grain boundary strengthening plays a significant contribution to the strength of the FSP treated AZ91. FSP treatment altered the failure mechanism of the alloy from brittle cleavage-dominant mode to ductile dimple-dominant mode, which can increase the potential of cast Mg alloys to use in the safety-critical application. The significant improvement in energy absorption capability is a function of grain refining and the formation of ultra-fine sub-micron Mg₁₇Al₁₂ particles. The trends in mechanical properties of AZ91 treated by various severe plastic deformation approaches are disused.

AZ91合金，使用最广泛的镁合金铸造，显示出低强度/延展性和能量吸收弱，这是它的大晶粒尺寸的功能，并且一个粗的和的连续网络的存在β-Mg系₁₇的Al ₁₂金属间化合物。这项工作表明，搅拌摩擦加工（FSP）可以增强AZ91合金的强度和能量吸收能力。研究了FSP处理对各种潜在强化机制的影响，包括晶界，固溶体和亚微米颗粒强化机制。可以确定，晶界强化对经FSP处理的AZ91的强度起着重要作用。FSP处理将合金的破坏机理从脆性劈裂占优模式转变为延性凹痕占优模式，这可以增加铸造Mg合金用于安全关键型应用的潜力。能量吸收能力的显着提高是晶粒细化和超细亚微米Mg形成的函数₁₇ Al ₁₂颗粒。废弃了通过各种严重塑性变形方法处理的AZ91的机械性能趋势。