Cu-Fe合金因兼具高强度与高导电性潜力而备受关注,但传统熔铸法存在亚稳液相分离导致的成分偏析问题,且固溶Fe原子会显著降低Cu基体的电导率。为克服这些限制,本工作采用冷喷涂结合热处理和冷轧工艺,制备了具有高强度和高导电性的Cu-10Fe原位复合材料,揭示了处理过程中的微观结构演化规律,分析了复合材料的强化机制和导电机制。结果表明,冷喷涂沉积体呈现梯度纳米晶结构,即超细纳米Cu晶粒(80~800 nm)环绕微米级变形Fe晶粒(3.5~10 μm)和较为粗大的微米级Cu晶粒(1.5~10 μm)。热处理后,沉积体发生静态回复与再结晶,微米级变形Cu晶粒和Fe晶粒转变为等轴晶,超细纳米Cu晶粒长大成微米级等轴晶,同时生成退火孪晶Cu,位错密度显著降低。经过冷轧处理后,等轴晶沿轧制方向伸长,形成具有强<111>和<211>纤维织构的细长Cu晶粒,以及具有主导<110>织构的Fe纤维。经热-轧制处理后,冷喷涂Cu-10Fe沉积体中孔隙和界面结合不良的情况得到显著改善,获得了成分均匀无偏析、结构致密的Cu-10Fe原位复合材料。该材料具有良好的综合性能,抗拉强度为550 MPa,电导率为72%IACS。Cu-10Fe原位复合材料的高强度可归因于细晶强化、位错强化以及Fe纤维的载荷传递强化。在冷喷涂及后处理过程中,Cu-Fe沉积体中的Cu沉积颗粒与Fe沉积颗粒内部没有发生相互固溶,对于在不损失强度的情况下提高电导率起到关键作用。
Cu–Fe alloys are promising for electrical engineering
applications due to their ability to combine high strength with excellent
electrical conductivity. Conventional casting, however, suffers from severe
limitations: metastable liquid-phase separation during solidification causes
pronounced compositional segregation, while dissolved Fe atoms scatter
conduction electrons, significantly reducing the Cu matrix conductivity. To
address these issues, this study employs a novel fabrication route integrating
cold spraying (CS) with post-deposition heat treatment (HT) and cold rolling
(CR) to produce high-performance Cu–10Fe in situ composites. Spherical
gas-atomized Cu and Fe powders were mechanically mixed and deposited onto an Al
substrate using nitrogen propellant gas. The CS deposits underwent vacuum
annealing at 600 °C for 24 h, followed by severe CR with 99% thickness
reduction. Microstructural evolution, strengthening mechanisms, and electrical
conductivity were systematically characterized using SEM, EBSD and TEM/EDS. The
CS deposit exhibited a gradient nano-grained structure, comprising ultra-fine
Cu nanograins (80–800 nm) surrounding deformed micron-sized Fe grains
(3.5–10 μm) and coarser micron-sized Cu grains (1.5–10 μm), with low porosity
(0.13%). Subsequent HT induced static recrystallization in the Cu matrix,
producing equiaxed grains (~3.9 μm) and promoting recovery/recrystallization in
the Fe particles. Interestingly, HT increased porosity to 0.86% and weakened
some Cu/Fe interfaces, likely due to thermal expansion mismatch. Severe CR
(HTCR state) markedly transformed the microstructure: equiaxed grains elongated
along the rolling direction, forming Cu grains with strong <111> and
<211> fiber textures and Fe fibers with a dominant <110> texture.
This HTCR process enhanced interfacial bonding and reduced porosity to 0.09%,
yielding a dense composite. Importantly, no mutual solid solubility between the
Cu matrix and Fe fibers was observed, except for a narrow (~20 nm) atomic
diffusion layer at the interfaces, as confirmed by TEM/EDS. The absence of Fe
solute in Cu is critical for maintaining high electrical conductivity. The HTCR
composite exhibited an exceptional combination of properties: an ultimate
tensile strength of 550 MPa, far exceeding the CS (190 MPa) and HT (233 MPa)
states, and a high electrical conductivity of 72%IACS. Its remarkable strength
arises primarily from fine-grain strengthening, dislocation strengthening, and
load transfer strengthening via Fe fibers. Notably, the experimentally measured
strength (495 MPa) exceeds the calculated contribution from these mechanisms
alone (367 MPa), highlighting the significant role of hetero-deformation-induced
strengthening and potentially underestimated fine-grain strengthening from
sub-EBSD-resolution grains. Together, these mechanisms account for the
composite’s ultrahigh strength. The high electrical conductivity results from
the absence of Fe solute scattering in the Cu matrix, improved interfacial bonding
and pore elimination during HTCR, and the alignment of elongated Cu grains and
Fe fibers along the current path, minimizing electron-scattering interfaces.
Compared to conventionally fabricated Cu–Fe alloys (e.g., casting, powder metallurgy), the CS + HTCR Cu–10Fe composite
exhibits a superior strength–conductivity balance. This study demonstrates that
CS combined with tailored thermo-mechanical processing (HT + CR) provides an
effective, industrially viable route to high-strength, high-conductivity Cu–Fe
in situ composites with uniform composition and dense microstructure.