Prof. Paul H. Mayrhofer

TU Wien - Institute of Materials Science and Technology, Vienna, Wien, Austria

Prof. Paul H. Mayrhofer

TU Wien - Institute of Materials Science and Technology, Vienna, Wien, Austria

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Academic Career Length

29Years (1998-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 November 2006 in Progress in Materials Science

Journal Article

Microstructural design of hard coatings

Paul H. Mayrhofer

Christian Mitterer

Lars Hultman

Helmut Clemens

8 September 2003 in Applied Physics Letters

Journal Article

Self-organized nanostructures in the Ti–Al–N system

Paul H. Mayrhofer

Anders Hörling

Lennart Karlsson

Jacob Sjölén

Tommy Larsson

Lars Hultman

The phenomenon of age hardening could be evidenced in thin film applications. A model system,

{Ti}_{1−x} {Al}_{x} N

was chosen as such coatings are known for their excellent wear resistance enabling improved machining processes like high-speed and dry cutting. Here, we show unambiguously that metastable

{Ti}_{1−x} {Al}_{x} N

coatings initially undergo spinodal decomposition into coherent cubic-phase nanometer-size domains, causing an increase in hardness at elevated temperatures. These intermediate metastable domains transform into their stable phases TiN and AlN during further thermal treatment. Activation energies for the processes indicate defect-assisted segregation of Ti and Al. The findings are corroborated by ab initio calculations. A long-standing discussion on the thermal stability of this important class of ceramics is thus resolved.

1 February 2012 in Surface and Coatings Technology

Journal Article

Thermal stability and oxidation resistance of Ti–Al–N coatings

Li Chen

Jörg Paulitsch

Yong Du

Paul H. Mayrhofer

Ti1 − xAlxN coatings are widely used for wear resistant applications due to their excellent mechanical and thermal properties, which depend to a great extent on the Al content. Here, we concentrate on a comparative study of the effect of Al content on crystal structure, thermal stability and oxidation resistance of Ti1 − xAlxN coatings. In agreement to earlier studies, thermal annealing of the individual cubic (c) and wurtzite (w) structured metastable Ti1 − xAlxN coatings induces decomposition into their stable phases c-TiN and w-AlN. The decomposition process for c-Ti1 − xAlxN involves an intermediate formation of cubic Al-rich and Ti-rich domains which results in a hardness increase to 34.7 and 34.4 GPa for x = 0.52 and 0.62 when annealed at 950 and 900 °C, respectively. In general, coatings with an Al content closer to the solubility limit, exhibit an earlier decomposition process, and hence an earlier peak-hardness.

1 June 2006 in Scripta Materialia

Journal Article

Thermal stability of Al–Cr–N hard coatings

H. Willmann

Paul H. Mayrhofer

Per O. Å. Persson

A.E. Reiter

L. Hultman

Christian Mitterer

1 November 2006 in Journal of Applied Physics

Journal Article

Influence of the Al distribution on the structure, elastic properties, and phase stability of supersaturated Ti1−xAlxN

Paul H. Mayrhofer

Denis Music

J. M. Schneider

{Ti}_{1 - x} {Al}_{x} N

films and/or their alloys are employed in many industrial applications due to their excellent mechanical and thermal properties. Synthesized by plasma-assisted vapor deposition,

{Ti}_{1 - x} {Al}_{x} N

is reported to crystallize in the cubic NaCl

(c)

structure for AlN mole fractions below 0.4–0.91, whereas at larger Al contents the hexagonal ZnS-wurtzite

(w)

structure is observed. Here we use ab initio calculations to analyze the effect of composition and Al distribution on the metal sublattice on phase stability, structure, and elastic properties of

c - {Ti}_{1 - x} {Al}_{x} N

and

w - {Ti}_{1 - x} {Al}_{x} N

. We show that the phase stability of supersaturated

c - {Ti}_{1 - x} {Al}_{x} N

not only depends on the chemical composition but also on the Al distribution of the metal sublattice. An increase of the metastable solubility limit of AlN in

c - {Ti}_{1 - x} {Al}_{x} N

from 0.64 to 0.74 is obtained by decreasing the number of Ti–Al bonds. This can be understood by considering the Al distribution induced changes of the electronic structure, bond energy, and configurational entropy. This may in part explain the large variation of the metastable solubility limit reported in the literature.

21 March 2005 in Applied Physics Letters

Journal Article

Self-organized nanocolumnar structure in superhard TiB2 thin films

Paul H. Mayrhofer

Christian Mitterer

J. G. Wen

J. E. Greene

I. Petrov

{TiB}_{2}

thin films are well known for their high hardness which makes them useful for wear-resistant applications. Overstoichiometric

{TiB}_{2}

deposited at 300 °C by nonreactive sputtering has been shown to exhibit superhardness

(H ⩾ 40 GPa)

, while the hardness of their bulk stoichiometric counterparts is

\sim 25 GPa

. We show, using high-resolution transmission electron microscopy, that overstoichiometric

{TiB}_{2.4}

layers have a complex self-organized columnar nanostructure. The

\sim 20 nm

wide columns, encapsulated in excess B and oriented along 0001, consist of a bundle of

\sim 5 nm

diameter

{TiB}_{2}

subcolumns separated by an ultrathin B-rich tissue phase. The nanocolumnar structure, which is thermally stable to postannealing temperatures up to 700 °C, inhibits nucleation and glide of dislocations during hardness indentation measurements, while the high cohesive strength of the B-rich tissue phase prevents grain-boundary sliding. The combination of these effects results in the observed superhardness of

\sim 60 GPa

About Me

Paul H. Mayrhofer is University Professor of Materials Science at TU Wien, Vienna, since 2012. He received his doctorate in Materials Science from the University of Leoben in 2001 and his habilitation in 2005. In 2025, he obtained a further habilitation in Materials Physics at TU Wien, reflecting his contributions to the fundamental understanding of metastable materials, defects, interfaces, and phase transformations. His postdoctoral research included an Erwin–Schrödinger Fellowship at the University of Illinois at Urbana–Champaign, RWTH Aachen University, and Linköping University. His research has advanced vapor-phase deposited ceramic materials from empirical optimization towards mechanism-based design. He pioneered the understanding of age hardening in ternary nitride and boride thin films and established design concepts based on metastability, phase transformations, interfaces, and engineered defects. His work spans adaptive coatings, superhard and tough nanostructured ceramics, superlattices, high-entropy materials, and defect-engineered ceramics. He introduced advanced methodologies for thin-film materials science, including high-temperature calorimetry, small-angle neutron scattering (SANS) for PVD coatings, atom probe tomography, substrate-independent fracture mechanics, and integrated DFT–experiment approaches. Paul Mayrhofer is Fellow of AVS, recipient of the START Prize and Bill Sproul Award, and elected member of the Austrian Academy of Sciences.

Prof. Paul H. Mayrhofer

Prof. Paul H. Mayrhofer

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