Cheng Jianyi, Yu Fangxin, Huang Fu
School of Materials Science and Engineering, Nanchang University, Nanchang 330031, China.
Materials (Basel). 2021 Jan 13;14(2):368. doi: 10.3390/ma14020368.
Cu-Ni-Si alloys are widely used in electrical and electronic industry owing to excellent electrical conductivity and strength. A suitable addition of Co in the Cu-Ni-Si alloys can improve its strength and deteriorate its electrical conductivity. In this work, Cu-Ni-Co-Si-P-Mg alloys with different Co content are employed to investigate the effects of Co on the properties and microstructure. The results showed that Co addition lead to the formation of (Ni, Co)Si precipitates. (Ni, Co)Si precipitate is harder to coarsen than δ-Ni2Si during aging. The larger the Co content in the alloys is, the smaller the precipitates formed is. There exists a threshold content of Co to divide the studied alloys into two groups. One group of theses alloys with <1 wt.% Co or Co/Ni ratio <0.56 has the same aging behavior as the Cu-Ni-Si-P-Mg alloy. On the contrary, the time to reach the peak hardness of aging for another group can be obviously delayed and its electrical conductivity decreases slightly with the increase of Co content. It can be attributed to the lower diffusion rate of Co than that of Ni in the Cu matrix. Meanwhile, the Co addition can inhibit the formation of P-enriched Ni-P phase in Co-containing alloys during aging. The as-quenched Cu-1.6Ni-1.2Co-0.65Si-0.1P-0.05Mg alloy can reach 257 HV and 38.7%IACS after aging at 500 °C for 3 h, respectively.
铜镍硅合金由于具有优异的导电性和强度而广泛应用于电气和电子工业。在铜镍硅合金中适当添加钴可以提高其强度，但会降低其导电性。在本工作中，采用不同钴含量的铜镍钴硅磷镁合金来研究钴对性能和微观结构的影响。结果表明，添加钴会导致形成（镍，钴）硅析出相。在时效过程中，（镍，钴）硅析出相比δ-Ni2Si更难粗化。合金中钴含量越高，形成的析出相越小。存在一个钴的临界含量，将所研究的合金分为两组。一组钴含量<1 wt.%或钴/镍比<0.56的合金具有与铜镍硅磷镁合金相同的时效行为。相反，另一组达到时效峰值硬度的时间会明显延迟，并且其电导率随着钴含量的增加而略有下降。这可归因于钴在铜基体中的扩散速率低于镍。同时，添加钴可以抑制含钴合金在时效过程中富磷镍磷相的形成。经500℃时效3小时后，淬火态的Cu-1.6Ni-1.2Co-0.65Si-0.1P-0.05Mg合金的硬度分别可达257 HV，电导率可达38.7%IACS。
