Availableonlineatwww.sciencedirect.com DIRECT E噩≈3S SEVIER Journal of the European Ceramic Society 25(2005)301-311 www.elsevier.com/locate/jeurceramsoc Mechanical and microstructural characterization of calcium aluminosilicate(CAS)and Sio2/Cas composites deformed at high temperature and high pressure Shaocheng Jia, d, * Erik Rybackib, Richard Wirth, Zhenting Jiang, Bin Xia d a departement des Genies Civil, Geologique et des Mines, Ecole Polytechnique de montreal, Montreal, Canada H3C 3A7 b GeoForschungsZentrum Potsdam, D-14473 Potsdam, germany e Department of Earth Sciences, University of Liverpool. Liverpool L69 3BX, Uk d laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry and South China Sea Institute of oceanography, Received 16 October 2003: received in revised form 18 February 2004; accepted 25 February 2004 Available online 21 July 2004 Abstract We performed axial compression experiments on polycrystalline calcium aluminosilicate(CAs or anorthite)and on particulate and layered composites with equal volume fractions of CAs and sio2(quartz) at a confining pressure of 300 MPa, temperatures of 1173-1473 K, and strain rates of 10-to 10-4s-I. The dense samples were fabricated from quartz crystalline and CAs glass powders by hot isostatic pressing (HIP). Under the experimental conditions, triclinic CAS, regardless in monolithic aggregates or composites, deforms by dislocation creep as indicated by TEM microstructures, intensive grain boundary migration recrystallization and strong crystallographic preferred orientation (CPO). Dislocation creep of CAs is characterized by dominant glide on a single slip system(0 10)[100] while mechanical twinning, anisotropic growth and recrystallization play an role to relieve the strain incompatibilities which would otherwise result from such limited slip systems. Particulate and particularly layered composites are significantly stronger than monolithic CAS aggregates, indicating that quartz is an effective reinforcement to the CAs matrix even when the material is used at high temperature and high pressure. Under layer-normal compression, the flow strength of layered composites increases remarkably with decreasing the thickness of the layers, and the thin-layered composites are significantly stronger than particulate counterparts with the same composition. The observed layering- induced stiffening is due to constraint effects of rigid quartz on plastic flow of CAs O2004 Elsevier Ltd. All rights reserved eywords: Composites; Mechanical properties; Hot isostatic pressing: Plasticity; Anorthite; SiO2 1. Introduction strain rates of 10-5 to 10-4s-I and a constant confining pressure of 300 MPa. Two main considerations on the merit In this paper we present our experimental results on the of this study should be mentioned in the following mechanical properties and microstructures of monolithic alcium aluminosilicate(CAs or anorthite: CaAl2Si3Og) aggregates, particulate and layered composites with equal (D)The CAS has been widely used as a matrix in fibre-or olume fractions of quartz(SiO2) and CAs, deformed in particle-reinforced ceramic composites that are excel axial compression(o1 >02=03>0, where o1, 02, 03 are lent prospective materials for application as mechanical the maximum, intermediate and least compressive princi- components in aerospace and automobile propulsion and pal stresses, respectively)at temperatures of 1173-1473K power systems. For better fabrication and application of such composites, it is essential to understand the rhe- ological properties, microstructures and textures of the author.Tel:+1-514-3404711x5134; CAS and various CAS-based ceramic composites de- fax:+1-514-3403970. formed under various conditions(T, P, flow strength and E-mail address: sji(apolymtl ca(. Ji) strain rate). Although a significant amount of work has 0955-2219/s-see front matter O 2004 Elsevier Ltd. All rights reserved doi: 10.1016/j jeurceramsoc 2004.02.018Journal of the European Ceramic Society 25 (2005) 301–311 Mechanical and microstructural characterization of calcium aluminosilicate (CAS) and SiO2/CAS composites deformed at high temperature and high pressure Shaocheng Ji a,d,∗, Erik Rybacki b, Richard Wirth b, Zhenting Jiang c, Bin Xia d a Département des Génies Civil, Géologique et des Mines, École Polytechnique de Montréal, Montréal, Canada H3C 3A7 b GeoForschungsZentrum Potsdam, D-14473 Potsdam, Germany c Department of Earth Sciences, University of Liverpool, Liverpool L69 3BX, UK d Laboratory of Marginal Sea Geology, Guangzhou Institute of Geochemistry and South China Sea Institute of Oceanography, Chinese Academy of Sciences, Wushan, Guangzhou 510640, PR China Received 16 October 2003; received in revised form 18 February 2004; accepted 25 February 2004 Available online 21 July 2004 Abstract We performed axial compression experiments on polycrystalline calcium aluminosilicate (CAS or anorthite) and on particulate and layered composites with equal volume fractions of CAS and SiO2 (quartz) at a confining pressure of 300 MPa, temperatures of 1173–1473 K, and strain rates of 10−5 to 10−4 s−1. The dense samples were fabricated from quartz crystalline and CAS glass powders by hot isostatic pressing (HIP). Under the experimental conditions, triclinic CAS, regardless in monolithic aggregates or composites, deforms by dislocation creep as indicated by TEM microstructures, intensive grain boundary migration recrystallization and strong crystallographic preferred orientation (CPO). Dislocation creep of CAS is characterized by dominant glide on a single slip system (0 1 0)[1 0 0] while mechanical twinning, anisotropic growth and recrystallization play an role to relieve the strain incompatibilities which would otherwise result from such limited slip systems. Particulate and particularly layered composites are significantly stronger than monolithic CAS aggregates, indicating that quartz is an effective reinforcement to the CAS matrix even when the material is used at high temperature and high pressure. Under layer-normal compression, the flow strength of layered composites increases remarkably with decreasing the thickness of the layers, and the thin-layered composites are significantly stronger than particulate counterparts with the same composition. The observed layering-induced stiffening is due to constraint effects of rigid quartz on plastic flow of CAS. © 2004 Elsevier Ltd. All rights reserved. Keywords: Composites; Mechanical properties; Hot isostatic pressing; Plasticity; Anorthite; SiO2 1. Introduction In this paper we present our experimental results on the mechanical properties and microstructures of monolithic calcium aluminosilicate (CAS or anorthite: CaAl2Si3O8) aggregates, particulate and layered composites with equal volume fractions of quartz (SiO2) and CAS, deformed in axial compression (σ1 > σ2 = σ3 > 0, where σ1, σ2, σ3 are the maximum, intermediate and least compressive princi￾pal stresses, respectively) at temperatures of 1173–1473 K, ∗ Corresponding author. Tel.: +1-514-3404711x5134; fax: +1-514-3403970. E-mail address: sji@polymtl.ca (S. Ji). strain rates of 10−5 to 10−4 s−1 and a constant confining pressure of 300 MPa. Two main considerations on the merit of this study should be mentioned in the following: (1) The CAS has been widely used as a matrix in fibre- or particle-reinforced ceramic composites that are excel￾lent prospective materials for application as mechanical components in aerospace and automobile propulsion and power systems.1–4 For better fabrication and application of such composites, it is essential to understand the rhe￾ological properties, microstructures and textures of the CAS and various CAS-based ceramic composites de￾formed under various conditions (T, P, flow strength and strain rate). Although a significant amount of work has 0955-2219/$ – see front matter © 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jeurceramsoc.2004.02.018