Phase transformations in nanocomposite ZrAlN thin films during annealing

Abstract

Nanocomposite Zr 0.52 Al 0.48 N 1.11 thin films consisting of crystalline grains surrounded by an amorphous matrix were deposited using cathodic arc evaporation. The structure evolution after annealing of the films was studied using high-energy x-ray scattering and transmission electron microscopy. The mechanical properties were characterized by nanoindentation on as-deposited and annealed films. After annealing in temperatures of 1050-1400°C, nucleation and grain growth of cubic ZrN takes place in the film. This increases the hardness, which reaches a maximum, while parts of the film remain amorphous. Grain growth of the hexagonal AlN phase occurs above 1300°C.

High temperature phase decomposition in TixZryAlzN

“…[1][2][3][4][5][6][7] However, additional heating, around 900 • C, will deteriorate the material properties when the AlN changes its structure from cubic to wurtzite. 8 In our previous works [9][10][11] we demonstrated that the addition of Cr into the solution leads to a formation of intermediate metastable phases of (TiCr)N and (CrAl)N where Cr dissolved in the AlN delays the onset of a detrimental cubic-to-wurtzite phase transition to higher temperatures, up to above 1000 • C. Another alloy that have shown interesting high temperature properties is (ZrAl)N. [12][13][14][15][16][17][18] Also, alloying (TiAl)N with Zr have been shown to give improved high temperature properties. [19][20][21][22] However, due to a very strong tendency towards phase separation between ZrN and AlN a process similar to what was seen in (TiCrAl)N is unlikely to play a major role in this system, instead some other decomposition trends should be expected.…”

Thermal stability of wurtzite Zr1−xAlxN coatings studied by in situ high-energy x-ray diffraction during annealing

“…2,3 Recent efforts at improving the thermal stability of these coatings have focused on ways to stabilize the cubic MeAlN phase, for example, alloying [7][8][9][10][11][12] or multilayer structures. 3,13,14 ZrAlN, a related MeAlN, also exhibits good high temperature properties [15][16][17][18][19][20][21][22][23] and, under specific circumstances, high toughness due to a stress-induced phase transformation. 24 The ZrAlN system exhibits an even larger miscibility gap between the binary cubic phases compared to TiAlN, 25 preventing the formation of a solid solution cubic structure during growth except for low Al-contents.…”

Wear behavior of ZrAlN coated cutting tools during turning

“…In the Zr0.50Al0.50N coating, no diffraction peaks was observed by XRD, which can be expected as ZrAlN coatings with similar composition commonly have a nanocomposite (nc) structure consisting of a mixture of small cubic and hexagonal structured grains and amorphous phases [16,22].…”

“…Table II). The nanocomposite structure of the nc-Zr0.50Al0.50N coating also results in a lower hardness than that of the other coatings probably due to more pronounced grain boundary sliding [35] and perhaps even a less dense material [22]. The lowest wear rate is observed for the w- [36].…”