有色金属工程（有色金属（中英文））

以Nb粉和电解Cu粉为原料，采用放电等离子烧结法，制备了Nb质量分数分别为1%、2%、3%及4%的铜基复合材料。通过显微组织观察和电导率、密度、硬度等测试，探讨了不同Nb含量对Nb-Cu复合材料的影响。研究表明：随着Nb含量的增加，铜基复合材料电导率下降，硬度上升。当Nb含量为4%时，材料硬度最大为60.6 HV，电导率为84.9%IACS；当Nb含量为1%时，材料硬度最小为46.1 HV，电导率最大为90.1%IACS。Nb含量的增加能够有效细化铜晶粒尺寸，抑制再结晶的进程，并提升小角度晶界的占比。Nb对铜基复合材料的强化方式为弥散强化、细晶强化、固溶强化。

Copper and its alloys are fundamental to modern industrial society,serving as critical materials in sectors ranging from power transmission and electronics to transportation and heavy machinery. This widespread application stems from their exceptional electrical and thermal conductivity,coupled with good corrosion resistance and excellent manufacturability. However,the ongoing technological advancement across these fields continuously elevates performance requirements,creating a pressing need for copper-based materials that possess superior mechanical strength and hardness without a significant compromise to their characteristic high conductivity. This pursuit of a better property balance has driven significant research into copper matrix composites,where a reinforcing phase is incorporated into the copper matrix to enhance its mechanical properties. Among various reinforcement options,niobium(Nb) has emerged as a particularly promising candidate for creating high-performance electrical contact materials and other critical electronic components. Nb offers an advantageous combination of high strength,good thermal stability,and limited solid solubility in copper,which is crucial for retaining high electrical conductivity. This study focuses on the fabrication of Nbreinforced copper matrix composites via the Spark Plasma Sintering(SPS) technique. SPS is an advanced consolidation method known for its ability to achieve high-density materials with refined microstructures through the simultaneous application of pulsed direct current and uniaxial pressure,which enables rapid sintering and minimizes grain growth. A systematic and comprehensive investigation was conducted to elucidate the precise effects of Nb content variation on the microstructure,electrical conductivity,and mechanical properties of the spark plasma sintered copper matrix composites. The experimental results demonstrate a clear,consistent,and quantifiable trend across all measured parameters:with a systematic increase in Nb mass fraction from 1% to 4%,the Vickers hardness of the composite material exhibited a substantial and progressive enhancement,rising significantly from 46. 1 HV to a maximum value of 60. 6 HV,representing an increase of approximately 31. 5%. Conversely,the electrical conductivity displayed a complementary yet inverse relationship,undergoing a gradual and predictable decrease from an optimal value of 90. 1% IACS to a still-respectable 84. 9% IACS. This characteristic inverse correlation between mechanical strength and electrical conductivity is a well-documented phenomenon in metal matrix composites and can be primarily attributed to the enhanced scattering of conduction electrons at the increased density of interfaces introduced by the Nb reinforcements,including grain boundaries and particle-matrix interfaces,coupled with the scattering effect caused by any Nb solute atoms dissolved within the copper lattice that create lattice strain fields. The microstructural examination provided further evidence for this behavior,revealing that higher Nb contents effectively refined the copper grain structure and increased the proportion of low-angle grain boundaries,which contributed simultaneously to the mechanical strengthening through the Hall-Petch mechanism and the electrical conductivity reduction through enhanced electron scattering phenomena. Microstructural analysis provided critical insights into the mechanisms behind the mechanical enhancement. It was found that the addition of Nb effectively refines the copper grain size by pinning grain boundaries and inhibiting the process of recrystallization during sintering. Furthermore,Electron Backscatter Diffraction(EBSD) analysis revealed that a higher Nb content leads to an increased proportion of low-angle grain boundaries,which are associated with the formation of sub-grain structures and contribute to strengthening. The primary strengthening mechanisms afforded by the Nb reinforcement were identified as fine grain strengthening,following the Hall-Petch relationship,and solid solution strengthening,where dissolved Nb atoms create lattice strain fields that impede dislocation motion. In conclusion,this work successfully demonstrates that Nb-reinforced copper matrix composites with a tailorable property profile can be efficiently fabricated using Spark Plasma Sintering. By varying the Nb content,it is possible to strategically balance the trade-off between hardness and conductivity,enabling the design of advanced materials suited for demanding applications in electrical and electronic engineering where both mechanical durability and efficient electrical performance are paramount.