CAJ | 학술논문

研究2A97铝锂合金的疲劳裂纹萌生及早期扩展行为。在室温条件下，采用光滑试样进行疲劳测试，其中最大应力为恒定值，应力比R为0.1，频率f 为40 Hz。利用金相显微镜、透射电镜、扫描电镜及电子背散射衍射等手段对合金的微观组织进行分析，研究合金的疲劳裂纹萌生及早期扩展行为与其微观组织的关系。结果表明：2A97合金的疲劳裂纹主要萌生于试样表面的杂质相和粗大第二相处；其疲劳裂纹的早期扩展行为主要受晶粒结构与位错或滑移带共同作用的影响。当相邻晶粒的错配度接近于其晶内的最优滑移面的位向差时，大角度晶界强烈阻碍滑移带的运动，从而导致裂纹分叉和偏折。
연구2A97려리합금적피로렬문맹생급조기확전행위。재실온조건하，채용광활시양진행피로측시，기중최대응력위항정치，응력비R위0.1，빈솔f 위40 Hz。이용금상현미경、투사전경、소묘전경급전자배산사연사등수단대합금적미관조직진행분석，연구합금적피로렬문맹생급조기확전행위여기미관조직적관계。결과표명：2A97합금적피로렬문주요맹생우시양표면적잡질상화조대제이상처；기피로렬문적조기확전행위주요수정립결구여위착혹활이대공동작용적영향。당상린정립적착배도접근우기정내적최우활이면적위향차시，대각도정계강렬조애활이대적운동，종이도치렬문분차화편절。
The fatigue crack initiation and early propagation behavior of 2A97 Al-Li alloy was studied. The smooth specimens were fatigued at room temperature under constant maximum stress control when stress ratio (R) is 0.1 and frequency (f) is 40 Hz. Microstructure observations were examined by optical microscopy, transmission electron microscopy, scanning electron microscopy and electron back scattered diffusion, in order to investigate the relationship between microstructure and fatigue crack initiation and early propagation behavior of 2A97 alloy. The results show that the fatigue cracks are predominantly initiated at inclusions and coarsen secondary phases on the surface of 2A97 alloy. The fatigue crack early propagation behavior of 2A97 alloy is predominantly influenced by the interactions between grain structure and dislocations or persistent slip bands (PSBs). When the misorientation of two neighbouring grains is close to the orientations of the favorable slip plane within these two grains, high-angle grain boundary severely hinders the PSBs passing through, and thus leads to crack bifurcation and deflection.