Design of Twinning Induced Plasticity (TWIP) Magnesium Alloys

镁合金是最轻的结构金属，其密度比铝合金轻近34%，因此对于迫切需要提高燃料效率的汽车和航空航天应用非常有吸引力。然而，通过对铝合金有效的常规合金设计方法来强化镁合金已被证明是困难的。镁合金的延展性也很低，这导致在室温下的可成形性差。镁合金的低强度和低塑性限制了其工业应用，需要新的合金设计和加工策略来克服这些障碍。该奖项支持镁合金设计新方案的基础研究，该方案偏离了传统方法，并有可能导致高强度，韧性镁合金。计算机模拟和实验将结合起来，以确定合金元素，可以导致高强度和延展性。这项研究的结果将为新型镁合金的设计提供指导，从而提高车辆的燃油效率并减少排放。在教学上，该项目为工程专业学生提供了一个机会，进行合金设计的计算机模拟和实验研究。孪晶诱导塑性在高锰浓度钢中实现高强度和延展性方面非常有效，其中机械孪晶是应变诱导的，有助于塑性流动和硬化，从而获得上级机械性能。与此形成鲜明对比的是，孪生诱导塑性的应用在镁合金中是缺乏的，尽管事实上，丰富的孪生可以被激活，因为孪生是应力诱导在这些合金中的低应力水平。因此，要在镁合金中引入孪生诱导塑性，必须提高孪生临界应力。在本研究项目中，将进行第一性原理计算，以确定对镁合金的c/a比和变形孪晶过程中原子重排的能垒有显着影响的合金元素。这些参数控制孪晶形核和生长的临界应力。在确定这些合金元素之后，将进行合金合成和热机械处理，以实现最佳的机械性能。这一策略为高性能镁合金的可持续设计和加工打开了一扇新的窗口，而无需求助于昂贵的外来合金元素。

Magnesium alloys are the lightest structural metals with densities near 34% lighter than aluminum alloys, and are thus very attractive for automotive and aerospace applications where improved fuel efficiency is urgently needed. However, strengthening magnesium alloys through the conventional alloy design approaches that are effective for aluminum alloys has proved difficult. The ductility of magnesium alloys is also low, which results in poor formability at room temperature. The low strength and ductility have limited the industrial applications of magnesium alloys, and new alloy design and processing strategies are needed to overcome these barriers. This award supports fundamental research for a new scheme for magnesium alloy design that departs from conventional approaches, and has the potential to lead to high-strength, ductile magnesium alloys. Computer simulations and experiments will be combined to identify alloying elements that can lead to high strength and ductility. The outcome of this research will provide guidelines for design of new magnesium alloys, leading to improved fuel efficiency of vehicles and reduced emissions. Educationally, this project provides an opportunity for engineering students to conduct computer simulations and experimental studies for alloy design.Twinning induced plasticity is very effective in achieving high strength and ductility in steels with high manganese concentrations in which mechanical twinning is strain-induced and contributes to the plastic flow and hardening, resulting in superior mechanical properties. In stark contrast, application of twinning induced plasticity is lacking in magnesium alloys, despite the fact that profuse twinning can be activated, because twinning is stress-induced at low stress levels in these alloys. Thus, to introduce twinning induced plasticity into magnesium alloys, the critical stress for twinning must be increased. In this research project, first principles calculations will be performed to identify alloying elements that have significant influences on the c/a ratio of magnesium alloys and the energy barrier for atomic shuffling during deformation twinning. These parameters control the critical stress for twin nucleation and growth. After these alloying elements are identified, alloy synthesis and thermomechanical processing will be conducted to achieve the optimal mechanical properties. This strategy opens a new window for sustainable design and processing of high performance magnesium alloys without resorting to expensive and exotic alloying elements.