W25Fe25Ni25Mo25高熵合金高速侵彻细观结构演化特性

为了探究W₂₅Fe₂₅Ni₂₅Mo₂₅高熵合金弹体在侵彻过程中宏观变形行为与材料微细观结构之间的联系, 基于对两相流动模型的简化, 建立了考虑软、硬相密度、流速以及浓度差异的等截面直管两相流动演化模型. 类比宏观状态下侵彻弹体头部材料的流入流出特性, 选定分析区域, 建立两相细观结构下材料在分析区域的流入流出关系, 再结合细观结构演化方程, 给出了分析区域中浓度演化结果, 提出了表征材料浓度演化速率的流动稳定系数t/l_length. 为了对比不同细观结构弹体的侵彻行为, 选取典型两相材料钨铜合金(W₇₀Cu₃₀), 基于小口径弹道枪发射平台开展两种弹体侵彻半无限钢靶试验, 对比两种合金弹体细观结构演化行为. 结果表明, 硬相浓度分布总体上体现“中心浓, 边缘稀”的特点; 硬相的浓度越高, 密度越大, 驱动速度越快, 则流动稳定系数t/l_length值越小, 侵彻过程中弹体的流动稳定性越好, 弹体头部材料越容易形成连续的塑性流动带. 等截面直管两相流动演化模型可用于描述侵彻过程中弹体头部材料的流动稳定性, 揭示了侵彻过程中弹体头部变形与细观两相结构之间的关联机制. 

EFFECT OF MICROSTRUCTURE ON FLOW BEHAVIOR DURING PENETRATION OF W25Fe25Ni25Mo25 HIGH-ENTROPY ALLOY PROJECTILE

In order to explore the relationship between the macro deformation behavior of W₂₅Fe₂₅Ni₂₅Mo₂₅ high-entropy alloy projectile and the micro structure of the material in the penetration, a two-phase flow evolution model of constant cross-section straight pipe is established. The model takes the differences of soft and hard phase density, velocity and concentration into consideration based on the simplification of the two-phase flow model. By analogy with the inflow and outflow characteristics of the materials at the head of the projectile in the macro state, the analysis area is selected. The inflow and outflow relationship of the materials in the analysis area under the two-phase microstructure is established. Combined with the microstructure evolution equation, the concentration evolution results in the analysis area are given. The flow stability coefficient t/l_length characterizing the concentration evolution rate of the materials is proposed. In order to compare the penetration behavior of projectiles with different microstructures, the typical two-phase material tungsten- copper alloy (W₇₀Cu₃₀) was selected to carry out the penetration test of two kinds of projectiles into semi-infinite steel target based on small caliber ballistic gun. The microstructure evolution behavior of the two kinds of alloy projectiles is analyzed. The results show that the distribution of hard phase concentration generally reflects the characteristics of "concentrated in the center and sparse at the edge". The higher the concentration of the hard phase, the higher the density and the faster the driving speed, the smaller the flow stability coefficient t/l_length. The better the flow stability of the projectile in the penetration, and the easier it is for the projectile head material to form a continuous plastic flow zone. The two-phase flow evolution model of constant cross-section straight pipe can be used to describe the flow stability of projectile head material in the process of penetration, and reveal the correlation mechanism between projectile head deformation and two-phase microstructure in the process of penetration.