Toughness enhancement in highly NbN-alloyed Ti-Al-N hard coatings

Strength, transformation toughening, and fracture dynamics of rocksalt-structure Ti1−xAlxNSangiovanni1, Tasnádi2, Johnson3 et al. 2020Phys. Rev. Materials

“…Over the past decades, several studies [8,[11][12][13][14][15][16][17][18] focused on understanding the surface reactivity and thermodynamics of phase segregation in order to design (Ti,Al)N-based coatings with superior thermal stability and hinder B1→B4 AlN-domain transformations [19][20][21]. In contrast, the toughness and resistance to fracture of (Ti,Al)N and (Ti,Al)N-based solid solutions have not been investigated as extensively, with a few studies available in the literature [22][23][24][25]. Recent experiments suggest that, although detrimental for the alloy hardness, the nucleation of wurtzite phases in B1 AlN-rich regions does not affect, or is even beneficial for, the coating toughness by inhibiting crack formation and/or propagation [26,27].…”

Effects of surface vibrations on interlayer mass transport: Ab initio molecular dynamics investigation of Ti adatom descent pathways and rates from TiN/TiN(001) islands

“…NaCl-structure (B1) TiN is a model system for transition-metal (TM) nitrides, a class of technologically important ceramic materials characterized by outstanding combinations of mechanical [23][24][25][26][27], physical [28,29], optical [30,31], electrical [32], and catalytic properties [33,34]. In addition, the properties can be tuned by varying TM compositions in alloys [32,[35][36][37][38] and/or the N/TM ratio [39][40][41][42][43] over wide ranges while preserving the cubic phase. AIMD simulations were used to separately determine the effects of varying the island area and temperature on adatom mobilities, as well as on Ti ad interlayer migration rates.…”

Enhanced thermal stability and fracture toughness of TiAlN coatings by Cr, Nb and V-alloying

“…Experimentally, the fracture toughness of Ti 1-x-y Al x (Nb) y N has been found to enhance with the addition of Nb [16]. With theoretical predictions based on the valence electron concentrations (VEC), the toughness of Ti 1-x-y Al x (V) y N also increases by V alloying [13,17].…”