高择优取向的单一LPSO相镁合金的制备、微观组织调控及其内耗影响机制的研究

This project takes aim at an academic problem that the contradictory between the damping and mechanical properties in magnesium alloy. And it is focusing on internal friction mechanism of long-period staking ordered (LPSO) phase in magnesium alloys, based the on the new phenomemon that LPSO phase can improve the strength and damping of magnesium alloy. The Mg-Zn (Ni)-Y alloys consisted of the highly preferred orientation single LPSO phase and close-packed hexagonal phase (HCP) phase of high purity magnesium will be as the research object. To beginning with, prepared the highly preferred orientation single LPSO phase and HCP phase according to directional solidification so as to measure the basic characteristic parameters of different direction ,such as critical resolved shear stress，shear modulus，strength and strain damping；then taking the special deformation and heat treatment to get some kinds of samples which come from typical dislocation type structure、twins type structure、grain boundary type structure and also contrastive analysis the influence discipline that the dislocation、twins、grain boundary to LPSO phase and HCP phase internal friction.At last ,considered all strain spectrum、frequecy spectrum、temperature spectrum of internal friction and the first principle calculation results of LPSO phase in order to clear internal friction mechanism of LPSO phase in Magnesium alloys. The project provide some reference for research and development of new magnesium alloys with high strength and high damping capacities,at the same time it can provide the reference of ideas and methods for researching strengthening and toughening mechanism of LPSO phase.

本项目针对长期困扰镁合金的阻尼性能与强度难以兼得的科学难题，基于实验中发现长周期有序相（LPSO）能同时提高镁合金阻尼性能和强度的新现象，以Mg-Zn(Ni)-Y合金和纯Mg作为研究对象，通过定向凝固制备出高择优取向的单一LPSO相和HCP相，测量其不同方向的临界分切应力、剪切模量、强度等基本特性参数；然后采用形变和热处理协同耦合技术调控得到几种具有典型单一位错型组织、孪晶型组织和晶界型组织的样品，并对比分析位错、孪晶和晶界等对LPSO相和HCP相内耗的影响规律；最后综合其内耗的应变谱、频率谱、温度谱和LPSO相的基本特性参数及层错能的第一性原理计算，澄清镁合金LPSO相的内耗影响机制。本项目为新型高强高阻尼镁合金研发提供新的思路和理论指导，也为弄清LPSO相的强韧化机制提供借鉴。

随着现代工业的迅猛发展，振动和噪声问题变得尤为突出，当前迫切需要一种高比强度兼具优异减振降噪性能的功能结构一体化材料。基于实验中发现长周期堆垛有序相（LPSO）能同时提高镁合金阻尼性能和强度的新现象，本项目以Mg-Zn (Ni) –Y合金和纯Mg为研究对象，通过合金成分设计、定向凝固技术、改变熔炼和变形工艺，研究了高择优取向单一长周期堆垛有序相（LPSO）的力学和阻尼特性、不同LPSO相含量及变形工艺对合金阻尼与力学性能的影响；通过研究不同热处理工艺对LPSO相形貌的调控以及对阻尼和力学性能的影响，总结了杆状模型和框架式模型两种阻尼与力学的平衡优化调控模型；采用形变与热处理耦合技术，制备了具有典型单一位错型、孪晶型和晶界型组织样品，揭示了位错、孪晶和晶界对LPSO相和HCP相内耗的影响规律。本项目为新型高强高阻尼镁合金的研发提供了理论指导，为澄清LPSO相的强韧化机制提供了借鉴，同时为阻尼镁合金在国防军工、航空航天和汽车等领域的应用奠定了基础。