Ab initio inspired design of ternary boride thin films

Abstract

The demand to discover new materials is scientifically as well as industrially a continuously present topic, covering all different fields of application. The recent scientific work on thin film materials has shown, that especially for nitride-based protective coatings, computationally-driven understanding and modelling serves as a reliable trend-giver and can be used for target-oriented experiments. In this study, semi-automated density functional theory (DFT) calculations were used, to sweep across transition metal diborides in order to characterize their structure, phase stability and mechanical properties. We show that early transition metal diborides (TiB2, VB2, etc.) tend to be chemically more stable in the AlB2 structure type, whereas late transition metal diborides (WB2, ReB2, etc.) are preferably stabilized in the W2B5−x structure type. Closely related, we could prove that point defects such as vacancies significantly influence the phase stability and even can reverse the preference for the AlB2 or W2B5−x structure. Furthermore, investigations on the brittle-ductile behavior of the various diborides reveal, that the metastable structures are more ductile than their stable counterparts (WB2, TcB2, etc.). To design thin film materials, e.g. ternary or layered systems, this study is important for application oriented coating development to focus experimental studies on the most perspective systems.

Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1−xTaxBy thin films

“…[13][14][15][16][17] Recently, TM diborides have been receiving increasing attention as the next generation of refractory, hard ceramic protective thin films for replacing TM nitrides in many applications. [18][19][20][21] TM diborides are already being employed as coatings on cutting tools [22][23][24][25] and engine components, [26][27][28] as well as for use as diffusion barriers in microelectronics. [29][30][31] While TM diborides are inherently hard, that alone is not sufficient to prevent failure in applications involving high stresses, since hardness is typically accompanied by brittleness leading to crack formation and propagation.…”

Microstructure and Properties of M3B2-Type Boride-Based Cermet Coatings Prepared by Laser Cladding Synthesis

“…These cermet coatings have already been applied to wear-and corrosion-resistant applications such as injection molding machine parts, bearings for sea water pumps, and offshore engineering parts [9]. In particular, as emerging and promising materials with superior strength, hardness, and wear and corrosion resistance, M 3 B 2 -type boride-based cermet coatings such as Mo 2 FeB 2 , Mo 2 NiB 2 , and W 2 NiB 2 as hard phases, are qualified candidates for applications in wear and corrosion resistance [10,11]. Takagi et al [12] found that M 3 B 2 (Mo 2 FeB 2 and Mo 2 NiB 2 )-based cermet coatings possessed excellent hardness and bonding properties, wear resistance, and corrosion resistance.…”

Synthesis and characterization of (Ti1-Al )B2+ thin films from combinatorial magnetron sputtering

“…In general, materials performance may be improved by synthesis of multicomponent systems, which allows tuning of the properties and control of the microstructure, resulting in overall enhanced functionality [10,11]. Various ternary systems of transition metal diborides are explored in order to obtain superior properties, e.g., W1−xTaxB2−z for a combination of both mechanical strength and ductility [12,13]. An example for hardcoating applications is Ti1-xAlxN, where Ti in TiN is partially replaced by Al, leading to age hardening effect through isostructural clustering, a primary reason behind its success [14].…”