The hardness, elastic modulus, and elastic recovery of nanostructured boride/nitride films 1–2 µm thick have been investigated by the nanoindentation technique under the maximum loads over a wide range (from 5 to 100 mN). It is demonstrated that only the hardness parameters remain constant at small loads (5–30 mN). The data obtained are discussed and compared with the parameters determined by other methods

Andrievskii, R A

Hellgren, Niklas

Kalinnikov, G V

Sandstrom, P

Shtanskii, D V

English

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Messiah University Mosaic Educator Scholarship & Departmental Newsletters Computing, Mathematics and Physics 9-1-2000 Nanoindentation and Strain Characteristics of Nanostructured Boride/Nitride Films Niklas Hellgren Messiah University, nhellgren@messiah.edu R A. Andrievskii G V. Kalinnikov P Sandstrom D V. Shtanskii www.Messiah.edu One University Ave. | Mechanicsburg PA 17055 Follow this and additional works at: https://mosaic.messiah.edu/mps_ed  Part of the Physics Commons Permanent URL: https://mosaic.messiah.edu/mps_ed/17 Recommended Citation Hellgren, Niklas; Andrievskii, R A.; Kalinnikov, G V.; Sandstrom, P; and Shtanskii, D V., "Nanoindentation and Strain Characteristics of Nanostructured Boride/Nitride Films" (2000). Educator Scholarship & Departmental Newsletters. 17. https://mosaic.messiah.edu/mps_ed/17 Sharpening Intellect | Deepening Christian Faith | Inspiring Action Messiah University is a Christian university of the liberal and applied arts and sciences. Our mission is to educate men and women toward maturity of intellect, character and Christian faith in preparation for lives of service, leadership and reconciliation in church and society. The basic ideas of investigating strain characteris-tics upon continuous indentation of an indenter were formulated in the mid-1970s (see, for example, [1–5]). This method has been extensively used in studies of films and surface layers, specifically upon nanoindenta-tion under small loads (see, for example, [6–9]). A great body of data on the hardness H and the elastic modulus E was obtained by the indentation technique. In partic-ular, valuable information on films based on interstitial phases (transition metal carbides, nitrides, and borides) was generalized in the review [10]. Interesting tech-niques of examining the microindentation kinetics were proposed by Golovin and Tyurin [11]. However, the observed dependences of H and E on the indenta-tion load P have yet to be unambiguously interpreted, and the reliability of the strain parameters is not univer-sally obvious and is not necessarily discussed. The sole exception is the work of Menchik et al. [9], who attempted to unify the techniques of determining E in nanoindentation experiments with ball diamond indent-ers. From general considerations and in relation to the study of size effects in nanostructured materials (spe-cifically in films) [12], it is important to reveal the degree of absolute reliability of the data obtained from nanoindentation measurements.As a continuation of our earlier work concerned with the determination of the hardness and elastic prop-erties of Ti(B,N) films by conventional methods [13], it was of interest to investigate the same films by the nanoindentation method. The conditions of magnetron sputtering and the characteristics of the Ti(B0.73N0.2O0.05C0.02)1.56 film (I) with a hexagonal structure of the AlB2 type and theTi(N0.49B0.34O0.12C0.05)1.49 film (II) with a cubic struc-tureof the NaCl type were given in [13]. Single-crystal silicon wafers were used as substrates. The film thick-nesses were δ I = 1.7–1.8 µ m and δ II = 1.2–1.3 µ m.The structural features were examined by the high-resolution transmission electron microscopy (JEM-3010). The crystallite sizes (L) were estimated on the basis of dark-field images as LI = 4–8 nm for film I and LII = 3–6 nm for film II. Figure 1 shows a micrograph obtained in the direct resolution mode. One can clearly see a characteristic fringe structure and the crystalline character of intercrystalline boundaries. These features were described in detail in our previous work [14].Nanoindentation and Strain Characteristics of Nanostructured Boride/Nitride FilmsR. A. Andrievskiœ, G. V. Kalinnikov, N. Hellgren, P. Sandstrom, and D. V. ShtanskiœAbstract—The hardness, elastic modulus, and elastic recovery of nanostructured boride/nitride films 1–2 µ m thick have been investigated by the nanoindentation technique under the maximum loads over a wide range (from 5 to 100 mN). It is demonstrated that only the hardness parameters remain constant at small loads (5− 30 mN). The data obtained are discussed and compared with the parameters determined by other methods. 5 nm101001Fig. 1. An image of the structure of film I in the direct resolution mode.        The nanoindentation measurements were carriedout on a Nano Indentor TM II instrument [15] with theuse of Berkovich trihedral diamond indenters. Themaximum loads Pmax were equal to 5, 10, 30, and100 mN. As before (see, for example, [16]), the load-ing–unloading procedure consisted in loading up toPmax, unloading down to 0.1Pmax, holding for 50 s,repeated loading to Pmax, holding for 200 s, and finalunloading. At least ten indentations were made for eachPmax load.Figure 2 illustrates the loading–unloading schemeand the estimation with the use of the measured param-eters. According to the known technique [7], theseparameters were used to evaluate H = Pmax/A, S =dP/dh, the elastic modulus of the “film + indenter” sys-tem E* = S /2( π /A)0.5, and the so-called elastic recoveryR = (hmax – hf)/hmax, where A is the indenter projectionarea determined from the maximum depth of indenterpenetration hmax. In turn, the elastic modulus of the filmEfilm was calculated from the relationship 1/E* = (1 –)/Eind + (1 – )/Efilm , where  νind  and  ν film  are thePoisson ratios of the indenter and the film (ν film  ~ 0.2),respectively; and  E ind  is the elastic modulus of theindenter (for diamond,  E  = 1141 GPa and  ν  = 0.07 [7]).The experimental loading–unloading curves for thestudied films are depicted in Fig. 3. The dependences ofthe strain characteristics on  P  are displayed in Fig. 4. Asfollows from the results obtained, only the hardness  His independent of P at small loads (P = 5–30 mN). TheR and E quantities in the studied P range increase witha decrease in the load. Note that brittle films I and II arealmost identical in the elastic recovery, i.e., the veryconventional parameter of brittleness (the perfect plas-ticity and the perfect elastic recovery correspond to R =0 and 1, respectively), whereas the hardnesses H andthe elastic moduli E of the films differ considerably.In this respect, it is of interest to compare the H andE quantities determined from the nanoindentation mea-surements with the experimental data obtained by con-ventional methods. According to [13], HI ~ 49 and EI  =460  ±  50 GPa for film I and HII ~ 49 and EII = 480 ±100 GPa for film II. The data on the hardness wereobtained with a PMT-3 microhardness tester at a load of0.3 N and were processed according to the proceduredescribed in [17], which made it possible to eliminatethe effect of a softer substrate and differences in filmthicknesses on the results of measurements. The Youngmoduli were determined by the contactless techniqueof measuring the elastic properties. A comparison ofthese data with the results demonstrated in Fig. 4 led tothe conclusion that different techniques of determiningH and E furnish the comparable results for film I,whereas the nanoindentation measurements for film IIgive the smaller parameters.However, this inference requires certain comments.It should be kept in mind that the hardness characteris-tics obtained in traditional measurements can be largerνind2νfilm2Load, nmPenetration, nmhmaxhfSPmaxFig. 2. Schematic representation of the dependences of theload on the penetration of an indenter under loading andunloading.10 20 30 40 50 60 701234512345Load, mNPenetration, nm(a)(b)(c)Penetration, nm100 200 300 40020406080100Load, mNFig. 3. Experimental loading–unloading curves at (a, b)Pmax = 5 mN and (c) Pmax = 100 mN for films (a, c) I and(b) II.than those determined by the nanoindentation tech-nique due to the known relaxation effect (the so-calledrecovered and unrecovered hardnesses). Moreover, it isworth noting that the thicknesses of the studied samplesdiffer, and, hence, the relative depths of indenter pene-tration h/δ are also different. For example, this ratio atP = 5 mN is equal to 0.034 for film I and 0.057 for filmII. At larger loads, this difference becomes all the moreevident, and the effect of the substrate should be takeninto account. In the general case, the scale effect, i.e.,the effect of the indentation load on the strain charac-teristics, can be due to the scaling violation [18] and theinhomogeneity of the surface layers in the studiedobjects. As follows from recent publications (see, forexample, [19–21]), the surface topography also playsan important part at very small loads (~10 mN andless). The investigation of the Ti(B,N) film surface bythe atomic-force microscopy [20] revealed that therelief of films II is more developed than that of films I,which can be partly responsible for a decrease in theestimates of H and E. Finally, the elastic modulus E evaluated from the nanoindentation data characterizes the strained state under conditions of nonuniform bulk compression. All these factors can affect the measured parameters, but this effect is difficult, if not impossible, to consider them quantitativelyIt should be noted that, unlike the results shown in Fig. 4, our earlier nanoindentation experiments [22] made on films I with the use of the first nanoindenter model [6] demonstrated a drastic increase in the hard-ness with a decrease in the load Pmax from 50 to 10 mN. On the other hand, the errors in measurements of the parameters, specifically of the hardness, sharply increased at small loads (less than 10–20 mN) [20, 23]. On this basis, it is clear that the reliability of strain parameters obtained from the nanoindentation data is rather conventional, and the contribution of possible effects should be considered in detail in each particular case.ACKNOWLEDGMENTSWe would like to thank Prof. J.-E. Sundgren and Prof. L. Hultman of the Linköping University (Swe-den) for their kind attention to the present study.This work was supported by the International Asso-ciation of Assistance for the promotion of cooperation with scientists from the New Independent States of the former Soviet Union (project INTAS no. 96-2232), the Program “Integration” (project no. 855), and the Pro-gram of the cooperation of the Russian Academy of Sciences and the Royal Swedish Academy of Sciences.~ ~~ ~~ ~10 20 30 90 1000.250.500.751.0025030035040045050025303540RE, GPaH, GPaLoad, mN(a)(b)(c)IIIFig. 4. Effect of the maximum load on (a) hardness, (b) elas-tic modulus, and (c) elastic recovery.12. R. A. Andrievskiœ and A. M. Glezer, Fiz. Met. Metallogr. 88, 50 (1999) [Phys. Met. Metallogr. 88, 45 (1999)].13. R. A. Andrievskiœ, G. V. Kalinnikov, N. P. Kobelev, et al., Fiz. Tverd. Tela (S.-Peterburg) 39, 1859 (1997) [Phys. Solid State 39, 1661 (1997)].14. R. A. Andrievskiœ, G. V. Kalinnikov, and D. V. Shtanskiœ, Fiz. Tverd. Tela (S.-Peterburg) 42 (4), 741 (2000) [Phys. Solid State 42, 760 (2000)].15. G. M. Pharr, W. C. Oliver, and F. R. Brotzen, J. Mater. Res. 7, 613 (1992).16. H. Liungcrantz, C. Engstrom, L. Hultman, et al., J. Vac. Sci. Technol. A 16, 3104 (1998).17. B. Jonsson and S. Hogmark, Thin Solid Films 114, 257 (1984).18. Yu. V. Mil’man, Probl. Prochn., No. 6, 52 (1990).19. X. Wang, A. K. Kolitsch, and W. Moller, Appl. Phys. Lett. 71, 1951 (1997). 20. R. A. Andrievski, in Surface-Controlled Nanoscale Materials for High-Added-Value Applications, ed. by K. E. Gonsalves, M.-E. Baraton, R. Singh, H. Hofmann,J. Chen, and J. Akkara (MRS, Warrendale, 1998), Mater. Res. Soc. Symp. Proc. 501, 149 (1998).21. R. A. Andrievski, J. Solid State Chem. 133, 249 (1997).22. R. A. Andrievskiœ, S. A. Amanulla, E. J. Brookes, et al., Neorg. Mater. 31, 1600 (1995) [Inorg. Mater. 31, 1456 (1995)].23. G. Shafirstein, M. Gee, S. Osgerby, and S. Saunders, in Thin Films—Stresses and Mechanical Properties V, ed. by Sh. Baker, C. Ross, P. Townsend, C. Volkert, andP. Borgesen (MRS, Warrendale, 1995), Mater. Res. Soc. Symp. Proc. 356, 717 (1995). Translated by O. Borovik-RomanovaReferences3. S. I. Bulychev, V. P. Alekhin, M. Kh. Shorshorov, and A. P. Ternovskiœ, Probl. Prochn., No. 9, 79 (1976).4. Yu. S. Boyarskaya, D. Z. Grabko, and M. S. Kats, Phys-ics of Microindentation Processes (Shtiintsa, Kishinev, 1986).5. S. I. Bulychev and V. P. Alekhin, Material Testing by Continuous Indentation of an Indenter (Mashinostroe-nie, Moscow, 1990).6. M. F. Doerner and W. D. Nix, J. Mater. Res. 1, 601 (1986).7. W. C. Oliver and G. M. Pharr, J. Mater. Res. 7, 1564 (1992).8. E. Soderlund and D. J. Rowcliffe, J. Hard Mater. 5, 149 (1994).9. J. Menchik, D. Munz, E. Quandt, et al., J. Mater. Res. 12, 2475 (1997).10. R. A. Andrievskiœ, Usp. Khim. 66, 57 (1997) [Russ. Chem. Rev. 66, 53 (1997)].11. Yu. I. Golovin and A. I. Tyurin, Kristallografiya 40, 884 (1995) [Crystallogr. Rep. 40, 818 (1995)]. 1.2.A. P. Ternovskiœ, V. P. Alekhin, M. Kh. Shorshorov, et al., Zavod. Lab. 39, 1242 (1973).S. I. Bulychev, V. P. Alekhin, M. Kh. Shorshorov, et al., Zavod. Lab. 41, 1137 (1975).

Nanoindentation and Strain Characteristics of Nanostructured Boride/Nitride Films

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Nanoindentation and Strain Characteristics of Nanostructured Boride/Nitride Films

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