Observation of etch pits in Fe-36wt%Ni Invar alloy

Abstract

To indirectly investigate the dislocation behavior of Fe-36wt%Ni Invar alloy by the etch pit method, polished Invar specimens were etched by a solution containing 4 g copper sulfate, 20 mL hydrochloric acid, and 20 mL deionized water for 2 min. Etch pits in the etched surfaces were observed. All the etch pits in one specific grain exhibited similar shapes, which are closely related to the grain orientations. These etch pits were characterized as dislocation etch pits. It was observed that etch pits arranged along grain boundaries, gathered at grain tips and strip-like etch pit clusters passed through a number of grains in the pure Invar specimens. After the addition of a small amount of alloying elements, the identification of a single dislocation etch pit is challenging compared with the pure Invar alloy. Thus, the observation of etch pits facilitates the investigation on the dislocation behavior of the pure Invar alloy. In addition, alloying elements may affect the densities and sizes of etch pits.

Keywords

Invar alloy / dislocations / etch pit technique / alloying elements

References

[1] Weyher JL, Brown PD, Rouvière JL, Wosinski T, Zauner ARA, Grzegory I. Recent advances in defect-selective etching of GaN. J. Cryst. Growth, 2000, 210(1–3): 151.

[2] Mukerji S, Kar T. Etch pit study of different crystallographic faces of L-arginine hydrobromide monohydrate (LAHBr) in some organic acids. J. Cryst. Growth, 1999, 204(3): 341.

[3] Tay FEH, Iliescu C, Jing J, Miao JM. Defect-free wet etching through pyrex glass using Cr/Au mask. Microsyst. Technol., 2006, 12(10–11): 935.

[4] Lee J, Kim J, Kim J, Lee J, Chung H, Tak Y. Effects of pretreatment on the aluminum etch pit formation. Corros. Sci., 2009, 51(7): 1501.

[5] Britt DW, Hlady V. In-situ atomic force microscope imaging of calcite etch pit morphology changes in undersaturated and 1-hydroxyethylidene-1, 1-diphosphonic acid poisoned solutions. Langmuir, 1997, 13(7): 1873.

[6] Appl. Phys. Lett., 2006, 89(13art.132117)

[7] Muto D, Araki T, Naoi H, Matsuda F, Nanishi Y. Polarity determination of InN by wet etching. Phys. Status Solidi A, 2005, 202(5): 773.

[8] Chen J, Wang JF, Wang H, Zhu JJ, Zhang SM, Zhao DG, Jiang DS, Yang H, Jahn U, Ploog KH. Measurement of threading dislocation densities in GaN by wet chemical etching. Semicond. Sci. Technol., 2006, 21(9): 1229.

[9] Wuu DS, Wu HW, Chen ST, Tsai TY, Zheng XH, Horng RH. Defect reduction of laterally regrown GaN on GaN/patterned sapphire substrates. J. Cryst. Growth, 2009, 311(10): 3063.

[10] Bondokov RT, Mueller SG, Morgan KE, Slack GA, Schujman S, Wood MC, Smart JA, Schowalter LJ. Large-area AlN substrates for electronic applications: an industrial perspective. J. Cryst. Growth, 2008, 310(17): 4020.

[11] Visconti P, Jones KM, Reshchikov MA, Cingolani R, Morkoc H, Molnar RJ. Dislocation density in GaN determined by photoelectrochemical and hot-wet etching. Appl. Phys. Lett., 2000, 77(22): 3532.

[12] Zhang ZH, Gao Y, Sudarshan T. Delineating structural defects in highly doped n-type 4H-SiC substrates using a combination of thermal diffusion and molten KOH etching. Electrochem. Solid State Lett., 2004, 7(11): G264.

[13] Hino T, Tomiya S, Miyajima T, Yanashima K, Hashimoto S, Ikeda M. Characterization of threading dislocations in GaN epitaxial layers. Appl. Phys. Lett., 2000, 76(23): 3421.

[14] J. Appl. Phys., 2008, 104(12)

[15] Pešička J, KuŽel R, Dronhofer A, Eggeler G. The evolution of dislocation density during heat treatment and creep of tempered martensite ferritic steels. Acta Mater., 2003, 51(16): 4847.

[16] Appl. Phys. Lett., 2007, 91(14)

[17] Kawamura F, Tanpo M, Miyoshi N, Imade M, Yoshimura M, Mori Y, Kitaoka Y, Sasaki T. Growth of GaN single crystals with extremely low dislocation density by two-step dislocation reduction. J. Cryst. Growth, 2009, 311(10): 3019.

[18] Hashimoto T, Wu F, Speck JS, Nakamura S. A GaN bulk crystal with improved structural quality grown by the ammonothermal method. Nat. Mater., 2007, 6(8): 568.