r - Ni 3(Al,Ti)합금 중에 불규칙 r 상의 석출 및단결정의 변형조직에 관한 연구

• 영문명: A Study on the Precipitation of Disordered r Phase in an L I2 Ordered 7 N i3 (A l，T i) Phase and Deformation Induced Microstructure of Single Crystals
• 발행기관: 호서대학교 공업기술연구소
• 저자명: 한창석(Chang-Suk Han)
• 간행물 정보: 『공업기술연구 논문집』제25권 제1호, 199~213쪽, 전체 15쪽
• 주제분류: 공학 > 공학일반
• 파일형태: PDF
• 발행일자: 2006.06.30

영문 초록

Optimum alloy compositions and heat treatments to obtain fine dispersion of disordered y particles in an L I 2 ordered T -Nis(Al, Ti), and the morphology change of 7 precipitates during aging have been investigated by means of transmission electron microscopy. A uniform solid solution of 7 -Ll2 ordered phase supersaturated with Ni can be obtained by solution annealing in a sui표 temperature range. The 7 phase hardens appreciably by the fine precipitation of disordered T. The shape of 7 precipitates formed during aging is initially spherical or round-cubic and grow into platelets as aging proceeds. High resolution electron microscopy revealed that the 7 precipitates are perfectly coherent with the matrix 7 r as long as the T-precipitates are plates. The loss of coherency initiates by the introduction of dislocations at the 7/7r interface followed by the step formation at the dislocations. The 7 precipitates become globular after the loss of coherency. The strength of T _Ni 3 (Al,Ti) increases over the temperature range of experiment by the precipitation of fine 7 particles. The peak temperature where a maximum strength was obtained shifted to higher temperature. Superlattice dislocations dissociate into fourfold Shockley partial dislocations in a uniform supersaturated solid solution of the 7 phase. Dislocations are attracted into the disordered 7 phase and dissociate further in the particles. At any stage of aging, dislocations cut through the particles and the Orowan bypassing process does not occur even in the over aged stage of this alloy system. The work necessary to pull the dislocation away from the disordered particles into the ordered matrix should mainly contribute to increase the strength of the ア phase containing fine dispersion of the disordered 7 phase.

목차

I . 서 론

II- 실험방법

in. 결과 및 고찰

IV. 결 론

키워드

LI 2 ordered phase intermetallic compound precipitation hardening superlattice dislocation