Contribution of Lattice Distortion to Solid Solution Strengthening in a Series of Refractory High Entropy Alloys
- PDF / 1,731,529 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 1 Downloads / 208 Views
Contribution of Lattice Distortion to Solid Solution Strengthening in a Series of Refractory High Entropy Alloys H. CHEN, A. KAUFFMANN, S. LAUBE, I.-C. CHOI, R. SCHWAIGER, Y. HUANG, K. LICHTENBERG, F. MU¨LLER, B. GORR, H.-J. CHRIST, and M. HEILMAIER We present an experimental approach for revealing the impact of lattice distortion on solid solution strengthening in a series of body-centered-cubic (bcc) Al-containing, refractory high entropy alloys (HEAs) from the Nb-Mo-Cr-Ti-Al system. By systematically varying the Nb and Cr content, a wide range of atomic size difference as a common measure for the lattice distortion was obtained. Single-phase, bcc solid solutions were achieved by arc melting and homogenization as well as verified by means of scanning electron microscopy and X-ray diffraction. The atomic radii of the alloying elements for determination of atomic size difference were recalculated on the basis of the mean atomic radii in and the chemical compositions of the solid solutions. Microhardness (lH) at room temperature correlates well with the deduced atomic size difference. Nevertheless, the mechanisms of microscopic slip lead to pronounced temperature dependence of mechanical strength. In order to account for this particular feature, we present a combined approach, using lH, nanoindentation, and compression tests. The athermal proportion to the yield stress of the investigated equimolar alloys is revealed. These parameters support the universality of this aforementioned correlation. Hence, the pertinence of lattice distortion for solid solution strengthening in bcc HEAs is proven. DOI: 10.1007/s11661-017-4386-1 The Minerals, Metals & Materials Society and ASM International 2017
I.
INTRODUCTION
SINCE the introduction of high entropy alloys (HEAs),[1] the focus has especially been on their microstructural and mechanical properties.[2] Solid solution strengthening in such chemically complex alloys is of particular interest,[3] as these systems typically exceed the constitutional range spanned by classical theories for the description of solid solution strengthening in dilute[4,5] and more concentrated[6] binary alloys. Accordingly, some efforts were made to develop models succeeding the current state of the description of solid solution strengthening.[7–10] The approach presented by
H. CHEN, A. KAUFFMANN, S. LAUBE, Y. HUANG, K. LICHTENBERG, and M. HEILMAIER are with the Institute for Applied Materials (IAM-WK), Karlsruhe Institute of Technology (KIT), Engelbert-Arnold-Str. 4, 76131 Karlsruhe, Germany. Contact email: [email protected] I.-C. CHOI and R. SCHWAIGER are with the Institute for Applied Materials (IAM-WBM), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany. F. MU¨LLER, B. GORR, and H.-J. CHRIST are with the Institut fu¨r Werkstofftechnik, Universita¨t Siegen, Paul-Bonatz-Str. 9-11, 57068 Siegen, Germany. Dedicated to Dr. Martin Palm on the occasion of his 60th birthday. Manuscript submitted June 29, 2017.
METALLURGICAL AND MATERIALS TRAN
Data Loading...
