Abstract

Nanostructured mechanical composites of immiscible metals Cu, Cr, and 5–70 wt % W; nanostructured consolidated materials based on them; and Cu/Cu–Cr–W nanostructured gradient material with various W contents are fabricated in this work by combining short-term (up to 150 min) high-energy ball milling (HEBM) and spark plasma sintering (SPS). To fabricate Cu–Cr–W mechanical composites, HEBM of Cu + Cr + (5–70 wt %)W is performed using an Activator-2S planetary ball mill with a revolution rate of drums of 1388 rpm and a planetary disc of 694 rpm in argon for 150 min. The Cu–Cr–W mechanical composites are consolidated by SPS at temperatures of 800–1000°C and pressure of 50 MPa for 10 min. The nanostructured gradient sintered material based on Cu–Cr–W pseudoalloys is compacted layer-by-layer in the following sequence (from pure copper to pseudoalloy with an increase in the tungsten weight fraction): Cu/Cu–Cr–5% W/Cu–Cr–15% W/Cu–Cr–70% W and sintered at 800°C for 10 min. The crystal structure, microstructure, and properties of Cu–Cr–W mechanical composites and consolidated materials based on them are investigated depending on fabrication conditions. It is shown that the nanostructure formed in mechanical composites at the short-term HEBM stage (up to 150 min) is retained after SPS for all Cu–Cr–W (5–70 wt % W) compositions. The SEM and EDS data evidence that W (d ~ 20–100 nm) and Cr (d ~ 20–50 nm) refractory particles are homogeneously distributed in the material bulk (in a copper matrix). The hardness of consolidated Cu–Cr–W samples (15 wt %) formed from nanostructured powder mixtures (after 150-min HEBM) by SPS at t = 800°C exceeds the hardness of samples sintered from the mixture of initial components (without HEBM) by a factor of ~6. The hardness for the nanostructured Cu–Cr–70% W composition (t_SPS = 1000°C) is higher by a factor of ~3 than for microcrystalline analogs. Samples Cu–Cr–15% W and Cu–Cr–70% W have the largest relative density up to 0.91. The resistivity of nanostructured Cu–Cr–W compositions exceeds this characteristic for microcrystalline samples approximately twofold. This can be caused by an increase in grain boundaries and the accumulation of various defects in the material at the HEBM stage. These results show the prospects of using the combination of short-term HEBM and subsequent SPS for the formation of consolidated nanocrystalline Cu–Cr–W composites and gradient materials based on them.

中文翻译：

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高能球磨-等离子烧结制备基于Cu-Cr-W伪合金的纳米梯度材料

摘要

不可混溶的金属Cu，Cr和5–70 wt％W的纳米结构机械复合材料；基于它们的纳米结构固结材料；通过结合短期（长达150分钟）高能球磨（HEBM）和火花等离子烧结（SPS）来制备具有不同W含量的Cu / Cu-Cr-W纳米结构梯度材料。为了制造Cu–Cr–W机械复合材料，使用Activator-2S行星式球磨机以1388 rpm的转鼓转速和694 rpm的行星盘进行Cu + Cr +（5-70 wt％）W的HEBM在氩气中150分钟。Cu-Cr-W机械复合材料在800-1000°C的温度和50 MPa的压力下通过SPS固结10分钟。基于Cu–Cr–W假合金的纳米结构梯度烧结材料按以下顺序逐层压实（从纯铜到钨重量分数增加的假合金）：Cu / Cu–Cr–5％W / Cu–Cr–15％W / Cu–Cr–70％W，在800°C烧结10分钟。根据制造条件，研究了Cu-Cr-W机械复合材料和基于它们的固结材料的晶体结构，微观结构和性能。结果表明，对于所有Cu–Cr–W（5–70 wt％W）组合物，在SPS后保留了在短期HEBM阶段（长达150分钟）内机械复合材料中形成的纳米结构。SEM和EDS数据证明W（根据制造条件研究了Cu-Cr-W机械复合材料和基于它们的固结材料的性能和性能。结果表明，对于所有Cu–Cr–W（5–70 wt％W）组合物，在SPS后保留了在短期HEBM阶段（长达150分钟）内机械复合材料中形成的纳米结构。SEM和EDS数据证明W（根据制造条件研究了Cu-Cr-W机械复合材料和基于它们的固结材料的性能和性能。结果表明，对于所有Cu–Cr–W（5–70 wt％W）组合物，在SPS后保留了在短期HEBM阶段（长达150分钟）内机械复合材料中形成的纳米结构。SEM和EDS数据证明W（d〜20-100纳米）和Cr（d〜20-50 nm）的耐火颗粒均匀分布在所述材料本体（在铜基质）。由纳米结构粉末混合物（在150分钟HEBM后）通过SPS在t = 800°C下形成的固结Cu-Cr-W样品（15 wt％）的硬度超过了从初始组分混合物（不含HEBM）烧结得到的样品的硬度）的〜6倍。纳米结构Cu–Cr–70％W成分的硬度（t _SPS= 1000°C）比微晶类似物高约3倍。样品Cu–Cr–15％W和Cu–Cr–70％W的最大相对密度最高为0.91。对于微晶样品，纳米结构的Cu–Cr–W组合物的电阻率超过了该特性的两倍。这可能是由于在HEBM阶段晶界的增加以及材料中各种缺陷的积累。这些结果显示了结合使用短期HEBM和后续SPS形成固结纳米晶Cu-Cr-W复合材料和基于它们的梯度材料的前景。