Review Internal residual stresses in glass-ceramics: A review Francisco C. Serbena a, ⁎, Edgar D. Zanotto b a Department of Physics, State University of Ponta Grossa (UEPG), CEP 84030-900, Ponta Grossa, PR, Brazil b Vitreous Materials Laboratory (LaMaV), Department of Materials Engineering, Federal University of São Carlos (UFSCar), CEP 13560-970, São Carlos, SP, Brazil abstract article info Article history: Received 5 December 2011 Received in revised form 18 January 2012 Available online 18 February 2012 Keywords: Residual stress; Glass-ceramic; Glass-matrix composite; Glass Internal residual stresses arise in glass-ceramics upon cooling down from the crystallization temperature. These stresses are due to the thermal expansion and the elastic mismatch between the crystalline and glassy phases. Therefore, the mechanical properties of glass-ceramics are likely to depend not only on their compo- sition and microstructure but also on the type (tension or compression) and magnitude of these residual stresses. In this work, we critically review the most commonly used theoretical models concerning residual stresses in glass-ceramics and glass-matrix composites, taking into consideration the effects of crystallized volume fraction, crystal shape and thermal expansion anisotropy. We also discuss most of the reported measurements of residual stresses in these dual-phase materials using different techniques, such as X-ray diffraction, nuclear magnetic resonance, Raman and fluorescence spectroscopy, and indentation. The available models and experimental results regarding spontaneous microcracking due to residual stresses are also discussed. Finally, guidelines for future work are suggested. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Important applications for glass-ceramics have been found in the domestic and high-technology markets [1–3]. Glass-ceramics com- bine the properties of crystalline ceramics with those of glasses and find applications in the telecommunications and optical industries, such as opto-electronic and microwave devices, surgical implants, dental materials, cooktops, and telescope mirrors [4–6]. Components with complex geometries can be molded in the glass phase at relatively low cost and with relatively simple technology [3]. Then, subsequent heat treatments can partially crystallize the glass object in a controlled manner with a designed microstructure and with very low or no porosity. The crystallized volume fraction can be as low as a few percent or as high as 99.5%. Generally, glass- ceramics have superior optical, chemical, electrical and mechanical properties to those of glasses and similar ceramics that have been produced by sintering. Glass-ceramics are thus produced by a controlled crystallization that leads to one or more phases embedded within a glassy matrix. Their mechanical, optical and thermal properties depend not only on their composition and microstructure but also on the thermal residual stresses that arise upon cooling due to the thermal and elas- tic mismatch between the precipitates and the glassy matrix [7]. In addition to these thermal micro stresses, residual macro stresses can arise due to non-homogeneous cooling, leading in some extreme cases to spontaneous cracking [4,6]. Therefore, an understanding of the thermal residual stresses in glass-ceramics and their relationships with the microstructure and overall mechanical properties of the ma- terials is important. The thermal residual stresses may have a signifi- cant impact on a material's mechanical performance including its strength [8–11] and stresses in composites [12–14], dental glass- ceramics [15–18] and components of fuel cells [19,20], among other applications. In this article, we critically review the most popular models for thermal residual stresses in dual-phase materials and their applications in glass-ceramics and glass-matrix composites consider- ing the effects of the thermal and elastic mismatch between the phases, crystallized volume fraction, precipitate shape, thermal expansion anisotropy and microcracking. We then discuss residual stress measurement using X-ray diffraction, nuclear magnetic reso- nance, Raman and fluorescence spectroscopy and indentation. Finally, we comment on previous experimental studies of microcracking due to residual stresses. The influence of residual stresses on fracture toughness and overall mechanical strength of glass-ceramics [21] will not be considered here. 2. Theoretical models for residual stresses 2.1. The Selsing model One of the simplest models to estimate internal residual stresses in glass-ceramics is that of Selsing [7]. It assumes that the precipitates (crystals) are spherical and isotropic and that the stress fields around Journal of Non-Crystalline Solids 358 (2012) 975–984 ⁎ Corresponding author at: Universidade Estadual de Ponta Grossa, Departamento de Física, Av. Carlos Cavalcanti, 4748, Ponta Grossa, PR, 84030-900, Brazil. Tel.: +55 42 3220 3044; fax: +55 42 3220 3042. E-mail address: fserbena@uepg.br (F.C. Serbena). 0022-3093/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2012.01.040 Contents lists available at SciVerse ScienceDirect Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/ locate/ jnoncrysol