## Abstract

Perovskite-type RRh_{3}B and RRh_{3}C (R = Y, Sc) form a continuous solid solution, RRh_{3}B_{x}C_{1-x}, in the range of 0 ≦ x ≦ 1 with cubic structure (space group: Pm3m, Z = 1). The values of the microhardness of YRh_{3}B_{x}C_{1-x} for x = 0, 0.25, 0.50, 0.75 and 1.00 are investigated as 4.4 ± 0.1, 4.9 ± 0.1, 5.5 ± 0.2, 6.4 ± 0.2 and 7.5 ± 0.15 GPa, respectively. On the other hand, the values of the microhardness of ScRh _{3}B_{x}C_{1-x} for x = 0, 0.25, 0.50, 0.75 and 1.00 are 4.5 ± 0.2, 6.1 ± 0.2, 7.4 ± 0.2, 8.9 ± 0.2 and 9.6 ± 0.1 GPa, respectively. Thus, the microhardness of RRh _{3}B_{x}C_{1-x} continuously becomes larger with increasing boron content. The oxidation onset temperatures of YRh _{3}B_{x}C_{1-x} for x = 0, 0.25, 0.50, 0.75 and 1.00 are 604, 631, 655, 687 and 978 K, respectively. On the other hand, the oxidation onset temperatures of ScRh_{3}B_{x}C_{1-x} for x = 0, 0.25, 0.50, 0.75 and 1.00 are 674, 675, 695, 725 and 753 K, respectively. Thermogravimetric analysis of the phase indicates that the oxidation onset temperature also increases with boron content. Thus, it appears that both mechanical strength and chemical stability of the RRh _{3}B_{x}C_{1-x} phase essentially depend on its boron content. Ab initio calculations have been performed to obtain the equilibrium lattice constants and the bulk moduli. The calculated lattice constants are in excellent agreement with experimental results.

Original language | English |
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Pages (from-to) | 375-378 |

Number of pages | 4 |

Journal | Journal of Alloys and Compounds |

Volume | 408-412 |

DOIs | |

Publication status | Published - 2006 Feb 9 |

Event | Proceedings of the Rare Earths'04 in Nara, Japan - Duration: 2004 Nov 7 → 2004 Nov 12 |

## Keywords

- Microhardness
- Oxidation resistance
- Perovskite-type phase
- ScRhB C
- YRhBC

## ASJC Scopus subject areas

- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry