摘要Cr--Nb nano-multilayered films with various modulation wavelengths Λ are prepared by e-gun evaporation and their mechanical properties are investigated. Cr and Nb both have bcc structures with large differences in lattice constants and Young's modulus, which are supposed to favour modulus enhancement. Nevertheless, nano-indention measurements show no enhancement for the modulus and a slight decrease for the hardness with decreasing Λ down to 6nm. This is mainly due to counter-contribution to modulus from adjacent layers subjected to reverse strains, in agreement with recent theoretical study, while the decrease of hardness arises from grain boundary sliding. Interestingly, at Λ= 3nm, the hardness of the film has an increase of 44% relative to the value of a rule of mixture, owing to the emergence of a new phase for reconciling the structure difference at the interfaces.
Abstract：Cr--Nb nano-multilayered films with various modulation wavelengths Λ are prepared by e-gun evaporation and their mechanical properties are investigated. Cr and Nb both have bcc structures with large differences in lattice constants and Young's modulus, which are supposed to favour modulus enhancement. Nevertheless, nano-indention measurements show no enhancement for the modulus and a slight decrease for the hardness with decreasing Λ down to 6nm. This is mainly due to counter-contribution to modulus from adjacent layers subjected to reverse strains, in agreement with recent theoretical study, while the decrease of hardness arises from grain boundary sliding. Interestingly, at Λ= 3nm, the hardness of the film has an increase of 44% relative to the value of a rule of mixture, owing to the emergence of a new phase for reconciling the structure difference at the interfaces.
YANG Meng-Jin;LAI Wen-Sheng;PAN Feng. Elastic Modulus and Hardness of Cr--Nb Nano-Multilayers[J]. 中国物理快报, 2007, 24(9): 2635-2638.
YANG Meng-Jin, LAI Wen-Sheng, PAN Feng. Elastic Modulus and Hardness of Cr--Nb Nano-Multilayers. Chin. Phys. Lett., 2007, 24(9): 2635-2638.
[1] Yang W M C, Tsakalakos T and Hilliard J E 1977 J Appl. Phys. 48 876 [2] Testardi L R et al %, Willens R H, Krause J T, McWhan D B and Nakahara S1981 J. Appl. Phys. 52 510 [3] Henein G E and Hilliard J E 1983 J. Appl. Phys. 54 728 [4] Tsakalakos T and Hilliard J E 1983 J. Appl. Phys. 54734 [5] Itozaki H I 1982 PhD Dissertation (Northwestern University) [6] Moreau A et al %, Ketterson J B and Mattson J1990 Appl. Phys. Lett. 56 1959 [7] Cammarata R C et al %, Schlesinger T E, Kim C, Qadri S B and Edelstein A S1990 Appl. Phys. Lett. 56 1862 [8] Fartash A et al %, Fullerton E E, Schuller I K, Bobbin S E, Wagner J W,%Cammarata R C, Kumar S and Grimsditch M1991 Phys. Rev. B 44 13760 [9] Baker S P and Nix W D 1994 J. Mater. Res. 9 3131 [10] Huang H B and Spaepen F 2000 Acta Mater. 48 3261 [11] Wu T B 1982 J. Appl. Phys. 53 5265 [12] Cammarata R C and Sieradzki K 1989 Phys. Rev. Lett. 622005 [13] Chu X and Barnett S A 1995 J. Appl. Phys. 77 4403 [14] Xu J H et al%, Kamiko M, Zhou Y M, Lu G H, Yamamoto R, Yu L H and Kojima I2002 Appl. Phys. Lett. 81 1189 [15] Cahn J W 1963 Acta Metall. 11 1275 [16] Li G Y et al %, Han Z H, Tian J W, Zhang L Q and Gu M Y2003 Rare Metal Mat. Eng. 32 1 [17] Gao N and Lai W S 2006 Chin. Phys. Lett. 23 2913 [18] Oliver W C and Pharr G M 1992 J. Mater. Res. 7 1564 [19] Oliver W C and Pharr G M 2004 J. Mater. Res. 19 3 [20] Danner R et al %, Huebener R P, Chun C S L, Grimsditch M and Schuller I K1986 Phys. Rev. B 33 3696 [21] Soe W H and Yamamoto R 1997 J Mater. Sci. Technol. 13245 [22] Kim C, Qadri S B, Scanlon M R and Cammarata R C 1994 ThinSolid Films 240 52 [23] Conrad H and Narayan J 2000 Scripta Mater. 42 1025 [24] Yip S 1998 Nature 391 532
2007, Vol. 24 
