Ti,C超过饱和固溶铝基复合薄膜的微结构和力学性能

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Ti,C SOLID SOLUTION SUPERSATURATED Al-BASED COMPOSITE FILMS

采用Al和TiC靶通过磁控共溅射方法制备了Ti:C≈1的不同Ti和C含量的铝基复合薄膜,研究了Ti和C含量对薄膜微观结构和力学性能的影响.结果表明:Ti和C的共同加入使复合薄膜形成了同时具有置换固溶和间隙固溶特征的"双超"过饱和固溶体,复合薄膜的晶粒尺寸在较低的溶质含量下就迅速减小到100 nm以下,并随溶质含量的增加继续减小.相应地,薄膜的硬度也从纯Al的1.3 GPa迅速提高,在含0.6%(Ti,C)时可达到2.1 GPa,并在含6.4%(Ti,C)时达到最高值7.0 GPa.随溶质含量的进一步提高,复合薄膜逐渐呈现非晶态,硬度也略有降低.研究结果显示了Ti和C双超过饱和固溶对铝基薄膜具有显著的晶粒细化作用和强化效果.

Alloy films could form substitutionally supersaturated solute solution because of the non-equilibrium characteristics of physical vapor deposition （PVD） and gained grain refining and me- chanical properties improving. In order to reveal the structure characteristics and strengthening effect of substitutionally and interstitially supersaturated solid solution films, a series of aluminum-based composite films with different Ti and C contents were synthesized by magnetron co-sputtering Al and TiC targets. EDS, XRD, TEM, STEM and nanoindenter were used to characterize the microstructure and mechanical properties of the composite films. The results showed that Ti and C dissolved in the grains with much higher solute contents than their solubility limits at thermodynamic equilib- rium state and enriched at the boundary. The composite film formed ＂dual-supersaturated solid solution＂ exhibiting both substitutional and interstitial features. In lower solute contents, the grain size of the composite film decreased to less than 100 nm rapidly because of severe lattice distortion. The hardness of the film increased to 2.1 GPa from pure Al 1.3 GPa when containing 0.6%（Ti, C）. With the increase of the solute contents, the film hardness increased gradually and achieved the highest value of 7.0 GPa when containing 6.4%（Ti, C）. Then the composite film transformed into amorphous and its hardness also slightly reduced. The study showed significant grain refining and strengthening effects of dual-supersaturation of Ti and C in lower content on aluminum-based film and provided a way to improve the mechanical properties of metal films.