Martensitic Transformation Temperatures of Ceramics

The renewed interest in shape memory and toughened ceramics for small‐scale applications makes the relationship between the chemistry of the ceramics and martensitic transformation temperatures (forward and reverse temperatures M s and A s ) of paramount importance. Dependence of transformation temperatures of the ceramics with shape memory effect and/or martensitic phase change on valence electron ratio (VER), number of valence electrons ( e v ), and average atomic number of the ceramics ( Z ) is investigated. Depending on chemical composition, the ceramics have average numbers of valence electrons (4.571 ≤ e v ≤ 5.667), Z = 13–29.333, and VER in the range of (0.17–0.44). A clear correlation of transformation temperatures to VER for most ceramics is found. M s and A s both decrease with increasing VER. Aliovalent doping alters e v and makes it influential in controlling the transformation temperatures. The influence of VER, e v , Z , and the suppressive effect of oversized solutes on M s is addressed.