서지주요정보
7075 알루미늄 합금의 기계적 성질 개선을 위한 Mn 첨가의 영향 = Effects of manganese on improving the mechanical properties of 7075 aluminum alloy
서명 / 저자 7075 알루미늄 합금의 기계적 성질 개선을 위한 Mn 첨가의 영향 = Effects of manganese on improving the mechanical properties of 7075 aluminum alloy / 최이성.
저자명 최이성 ; Choi, Yee-Seong
발행사항 [대전 : 한국과학기술원, 1993].
Online Access 원문보기 원문인쇄

소장정보

등록번호

8003799

소장위치/청구기호

학술문화관(문화관) 보존서고

MMS 93012

SMS전송

도서상태

이용가능

대출가능

반납예정일

초록정보

The mechanical behaviors of high strength aluminum alloys containing 5 - 5.3Zn, 2.2-2.5Mg, 1.4-1.6Cu, and 0.2-0.3Cr in weight percent have been investigated as a function of manganese contents in the range of 0.068, 0.97 weight percent. A role of adding manganese in Al-Zn-Mg-Cu alloy is to form 0.03 ~ 0.25㎛ fine Mn-rich dispersoids whose structure and composition have not been clearly identified and to increase strength owing to dispersion hardening particles without sacrificing ductility contributed by homogenizing slip distribution which leads to inhibiting planar slip and reducing local strain and/or stress concentration. In this study, the distribution of dispersoids was observed in use of TEM and the density of Mn-dispersoids was increased with increasing manganese contents without changing the morphology and the size of the dispersoids. And the observation of dislocation arrangements after 10 percent fatigue cycling showed that the degree of slip homogenization was increased as the density of Mn-dispersoids was increased, while Mn-free alloy showed inhomogeneous planar slip. Tensile test results showed increase in strength, but ductility was significantly decreased in Mn-bearing alloys. This can be explained by the detrimental effect of coarse inclusions formed by Fe impurity in Mn-bearing alloys compared to Mn-free alloy. In the tear tests of the alloys containg dispersoids fractured surface showed microdimples which are the characteristic feature by void initiation and coalescence. Toughness was not decreased linearly with increasing Mn-dispersoid density. So it can be concluded that toughness was dependent on not only void formation due to local stress concentration on second phase particles but strain homogenization by dispersoids So optimum toughness can be gained in moderate dispersoid density level. Fatigue cracks were initiated by inclusion/matrix debonding or on broken inclusions by strain concentration at the surface of specimen and propagated through matrix. So inclusion which mainly constisted of Fe and Si must be avoided to improve fatigue property as well as tensile properties. In the low cycle fatigue(LCF) 1.0wt.%Mn-bearing alloy had the best iterative stress resistance by dispersion hardening effect and slip homogenization due to Mn-dispersoids.

서지기타정보

서지기타정보
청구기호 {MMS 93012
형태사항 [iv], 71 p. : 삽도, 사진 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Yee-Seong Choi
지도교수의 한글표기 : 남수우
지도교수의 영문표기 : Soo-Woo Nam
학위논문 학위논문(석사) - 한국과학기술원 : 재료공학과,
서지주기 참고문헌 : p. 67-71
주제 Aluminum alloys.
Metals --Mechanical properties.
Fatigue.
알루미늄 합금. --과학기술용어시소러스
기계적 성질. --과학기술용어시소러스
첨가율 효과. --과학기술용어시소러스
Tear tests.
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