●" Science Direct Current Opinion in Solid state Materials science ELSEVIER Current Opinion in Solid State and Materials Science 9(2005)313-318 Martensitic transformation in zirconia containing ceramics and its applications School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030, China An introduction to tetragonal(t)- monoclinic(m) martensitic transformation in zirconia containing ceramics, especially tetragonal zirconia polycrystalline (TZP) was presented. Thermodynamics, crystallographic and kinetics of t-m martensitic transformation in TZP were emphasized. Transformation toughening and shape memory effect (SME) associated with t- m martensitic transformation in the TzP were reviewed. Perspective of future challenges was briefly mentioned at the end o 2006 Published by Elsevier Ltd Keywords: Martensitic transformation; TZP, Transformation toughening: Shape memory effect 1. Introduction Undoped zirconia exhibits the following phase trans tions under ambient during thermal cycling[7] Zirconia containing ceramics are materials of imparting toughness(known as transformation toughening [l] while m-ZrO2#t-Zro 2370oC c- ZrO2 liquid maintaining strength and chemical inertness, and of exhib- 950°C ing new functions such as shape memory effect [2] by It has been well documented that the t-m transformation manipulating new microstructure. These properties are is a athermal martensitic transformation, associated with a mainly dominated by the structure transformation from large temperature hysteresis(several hundred K), a volume tetragonal(t) to monoclinic(m) change or dilation component of transformation strain (4- Gale irconia containing ceramics can be classified into three 5%)and a large shear strain %or9)[6-*8 tegories: tetragonal zirconia polycrystalline(TZP), par- leads to disintegration of sintered undoped zirconia parts tially stabilized zirconia(PSZ) and zirconia toughened/ Dopants(yttria, ceria, etc. are added to stabilize the high dispersed ceramics(ZTC/ZDC). Tetragonal zirconia poly- temperature tetragonal and/or cubic phase in the sintered crystalline (TZP)is a material with nearly 100% t-ZrO2 microstructure 3] phase, stabilized by yttria or ceria additions [3]. An alterna In the view of the potential commercial applications [9] tive way to stabilize the tetragonal phase is to decrease the typically room temperature)of high temperature polymor grain size of tetragonal phase to nanoscale[*4, **5]. Grain phs (tetragonal and cubic)of ZrO2, the issues associated sizes of TZP ceramics are typically in the range of 0.2-1 um with t-m martensitic transformation, related mechanism [6]. These ceramics are often designated with the prefix with of transformation toughening and stabilization of metasta- Ce- or Y-to denote ceria- or yttria-stabilized, for example, gonal phase at lower temp 8Ce-0.5Y-TZP represents a 8 mol%CeO2 and 0.5 mol% much attention in both ceramic research and martensitic Y2O3 stabilized zirconia transformation worlds for three decades [1-**11]. In the present review, the author discusses characteris- tics of tetragonal(t)- monoclinic(m)martensitic trans- E-mailaddress:jin(@sjtu.edu.cn formation in TZP, the shape memory effect and the 1359-0286/s- see front matter 2006 Published by Elsevier Ltd. doi:l0.1016 cossms.2006.02012Martensitic transformation in zirconia containing ceramics and its applications Xue-Jun Jin School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200030, China Abstract An introduction to tetragonal (t) ! monoclinic (m) martensitic transformation in zirconia containing ceramics, especially tetragonal zirconia polycrystalline (TZP) was presented. Thermodynamics, crystallographics and kinetics of t ! m martensitic transformation in TZP were emphasized. Transformation toughening and shape memory effect (SME) associated with t ! m martensitic transformation in the TZP were reviewed. Perspective of future challenges was briefly mentioned at the end. 2006 Published by Elsevier Ltd. Keywords: Martensitic transformation; TZP; Transformation toughening; Shape memory effect 1. Introduction Zirconia containing ceramics are materials of imparting toughness (known as transformation toughening [1]) while maintaining strength and chemical inertness, and of exhib￾iting new functions such as shape memory effect [2] by manipulating new microstructure. These properties are mainly dominated by the structure transformation from tetragonal (t) to monoclinic (m). Zirconia containing ceramics can be classified into three categories: tetragonal zirconia polycrystalline (TZP), par￾tially stabilized zirconia (PSZ) and zirconia toughened/ dispersed ceramics (ZTC/ZDC). Tetragonal zirconia poly￾crystalline (TZP) is a material with nearly 100% t-ZrO2 phase, stabilized by yttria or ceria additions [3]. An alterna￾tive way to stabilize the tetragonal phase is to decrease the grain size of tetragonal phase to nanoscale [*4,**5]. Grain sizes of TZP ceramics are typically in the range of 0.2–1 lm [6]. These ceramics are often designated with the prefix with Ce- or Y- to denote ceria- or yttria-stabilized, for example, 8Ce–0.5Y–TZP represents a 8 mol% CeO2 and 0.5 mol% Y2O3 stabilized zirconia. Undoped zirconia exhibits the following phase transi￾tions under ambient during thermal cycling [*7]: m-ZrO2 )*1170 C 950 C t-ZrO2 )*2370 C c-ZrO2 )*2680 C liquid It has been well documented that the t ! m transformation is a athermal martensitic transformation, associated with a large temperature hysteresis (several hundred K), a volume change or dilation component of transformation strain (4– 5%) and a large shear strain (14–15% or 9) [6–*8]. This leads to disintegration of sintered undoped zirconia parts. Dopants (yittria, ceria, etc.) are added to stabilize the high temperature tetragonal and/or cubic phase in the sintered microstructure [3]. In the view of the potential commercial applications [9] (typically room temperature) of high temperature polymor￾phs (tetragonal and cubic) of ZrO2, the issues associated with t ! m martensitic transformation, related mechanism of transformation toughening and stabilization of metasta￾ble tetragonal phase at lower temperatures have drawn much attention in both ceramic research and martensitic transformation worlds for three decades [1–**11]. In the present review, the author discusses characteris￾tics of tetragonal (t) ! monoclinic (m) martensitic trans￾formation in TZP, the shape memory effect and the 1359-0286/$ - see front matter 2006 Published by Elsevier Ltd. doi:10.1016/j.cossms.2006.02.012 E-mail address: jin@sjtu.edu.cn Current Opinion in Solid State and Materials Science 9 (2005) 313–318