超低W-W连接度W-Cu-Zn新型合金的制备及动态力学性能研究

Due to the high density, high hardness and excellent thermal resistance, W-Cu alloy has great potential applications in warhead materials. However, the W-Cu alloy prepared by routine methods usually exhibit relatively low dynamic yielding strength and very poor ductility under tensile loading, which severely restricted the applications of W-Cu alloy in military field. In previous study, we made in-depth analysis on relationship between microstructure feature and mechanical properties of W-Cu alloy and found that,the W-W contiguity is the key factor for the dynamic ductility of W-Cu alloy, and the strength of Cu matrix is the key factor for the dynamic yielding strength of W-Cu alloy.In the present study,a new method base on combination of electroless Cu plating on the surfaces of tungsten powders and spark plasma sintering (SPS) methods is proposed to prepare the W-Cu-Zn alloy. The W-W contiguity of W-Cu-Zn alloy is controlled at a very low ratio, so as to enhance the ductility of W-Cu-Zn alloy under dynamic tensile loading,and element Zn added in the matrix can form precipitation phase with Cu, which is used to increase the dynamic yielding strength of W-Cu-Zn alloy. On this base of ultra-low W-W contiguity and addition of Zn, the preparation techniques of W-Cu-Zn alloy,the control method of W-W connected degree, the precipitation theory of Cu-Zn intermetallic compound in matrix and the dyanmic mechanical behaviours are systematically investigated. The results will provide theory and experimental base for the development of new tungsten heavy alloy and its applications on key military materials.

钨铜合金由于其高密度、高硬度和良好的耐热性能，在兵器领域拥有极高的应用潜力，但是常规方法制备的钨铜合金动态屈服强度较低，动态延伸率极差，严重制约了钨铜合金在兵器战斗部领域的应用。针对上述问题，申请人在本课题前期工作中深入研究了钨铜合金组织结构与力学性能的关系，发现W-W连接度是影响钨铜合金动态延伸率的关键因素，而铜基体相的强度是制约钨铜合金动态强度的关键因素。本课题旨在采用钨粉化学镀铜与SPS放电等离子烧结相结合的方法制备具有超低W-W连接度的W-Cu-Zn系新型钨合金，通过降低合金中W-W连接度，避免动拉伸载荷作用下W-W界面分离引起材料失效，以此提高合金动态延伸率；在粘结相中添加Zn元素，利用Cu-Zn析出相的强化作用提高合金的动态屈服强度。拟深入开展合金制备工艺、W-W连接度控制工艺、析出相调控机理和材料动态力学性能等方面的研究，为军用新型钨合金的研发和工程应用奠定理论和实验基础。

W-Cu合金由于其高密度、高硬度和良好的耐热性能，在兵器领域拥有广阔的应用潜力。常规粉末冶金方法或熔渗法制备的W-Cu合金动态屈服强度较低，动态延伸率极差，严重制约了W-Cu合金在兵器战斗部领域的应用。依基金申请书中所提研究计划并结合后续研究工作，申请人采用钨粉表面化学镀铜分别与“放电等离子烧结”、“冷等静压+放电等离子烧结”和“冷等静压+熔渗”三种方法结合制备了具有低W-W连接度的新型W-Cu-Zn合金，优化了制备过程中的主要工艺，对比分析了三种方法制备的W-Cu-Zn合金的准静态和动态力学性能，分别揭示了上述W-Cu-Zn合金的破坏机制，并研究了W-Cu-Zn合金穿甲弹芯对钢靶的侵彻能力。研究发现，相比于传统制备方法，采用钨粉表面化学镀铜与上述三种方法结合制备出的W-Cu-Zn合金的W-W连接度均显著降低，其中采用“钨粉表面化学镀铜+冷等静压+熔渗”制备出的W-Cu-Zn合金W-W连接度仅为10%，致密度大于98%。该合金动态抗压强度为1061MPa，动态临界破坏应变高于0.8，准静态拉伸延伸率可达7.8%，强度及塑性均显著优于具有相同成分的常规粉末冶金钨铜锌合金。靶试研究表明，W-Cu-Zn合金制备的动能弹芯材料具有优异的穿甲性能，其机理是该合金弹芯侵彻过程中具有穿甲“自锐化”特性，项目揭示了其“自锐化”特性的机理。综上所述，本项目成功解决了制约低钨含量钨铜系合金力学性能的两个关键问题，改善了界面强度及粘结相强度，为制备高强度、高塑性钨铜系合金提供了一个崭新的思路与技术途径，对W-Cu-Zn合金的工程应用尤其是在兵器领域的应用有一定的指导意义。