中文摘要：

研究Ni54Mn25Ga15Al6高温形状记忆合金的微观组织、马氏体相变特性、力学性能和形状记忆效应。通过与Ni54Mn25Ga21合金对比，分析添加第四组元Al对Ni-Mn-Ga合金性能的影响。结果表明：Ni54Mn25Ga15Al6合金为单一的四方结构非调制马氏体相并呈片状的马氏体孪晶板条形貌。该合金的马氏体相变开始温度超过190℃，具有发展成为高温形状记忆合金的潜力。在Ni-Mn-Ga合金中添加Al会降低马氏体相变温度，这主要归因于Al添加引入的晶格尺寸因素的改变。添加Al元素能有效提高合金的强度和塑性，但降低合金的形状记忆性能。

英文摘要：

The microstructure, martensitic transformation behavior, mechanical properties and shape memory effect of Ni54Mn25Ga15Al6 high-temperature shape memory alloy were investigated. By comparing with the Ni54Mn25Ga21 alloy, the effect of Al addition on the properties of Ni-Mn-Ga alloys was analyzed. The results show that the Ni54Mn25Ga15Al6 alloy has a single-phase tetragonal non-modulated martensite structure with lamellar twins. The martensitic transformation start temperature of this alloy is up to 190 ℃, displaying the promising application as a high-temperature shape memory alloy. Al addition in Ni-Mn-Ga alloy can decrease the martensitic transformation temperatures due to the effect of size factor and improve the strength and plasticity. However, the shape memory effect is reduced remarkably with the Al addition.