s時(shí)，沿著V型缺口的應(yīng)力集中部位或缺陷處會(huì)出現(xiàn)不同類型的熱疲勞裂紋，但有且只有1條主裂紋。當(dāng)裂紋尖端擴(kuò)展路徑與第二相顆粒長軸方向形成小于45°的夾角時(shí)，裂紋擴(kuò)展將沿著第二相顆粒的邊緣繼續(xù)向前擴(kuò)展；當(dāng)裂紋尖端擴(kuò)展路徑與第二相顆粒短軸方向形成小于45°的夾角時(shí)，裂紋將穿過第二相顆粒，繼續(xù)向前擴(kuò)展。;The thermal fatigue properties of multicomponent Al-7Si-0.3Mg aluminum alloys in three different treatment states at different temperatures were studied. The integral method and secant method were proposed to calculate the thermal fatigue crack propagation life, and the thermal fatigue crack growth behavior of the alloys was analyzed. The results indicate that the temperature change has a direct effect on the thermal fatigue crack propagation rate of the multicomponent Al-7Si-0.3Mg aluminum alloys. The thermal fatigue properties of the multicomponent Al-7Si-0.3Mg alloys with addition of Cu, Mn, Ti, and other elements after refinement and direct refinement are superior to those of the as-cast Al-7Si-0.3Mg alloys. The growth behavior of thermal fatigue cracks mainly includes the initiation and propagation of thermal cracks. The initiation of thermal fatigue crack requires a certain incubation period and the crack is generated at the V-notch. When the alternating thermal stress exceeds the yield strength σs of alloys, different types of thermal fatigue cracks appear at the stress concentration parts or at defects of the V-notch but with only one main crack. When the angle between the crack tip propagation path and the major axis direction of the second phase particle is less than 45°, the crack propagation extends further along the edge of the second phase particles; when the angle between the crack tip propagation path and the minor axis direction of the second phase particle is less than 45°, the crack passes through the second phase particle and extends forward."/>