Effect of Micro-scale Y Addition on the Fracture Properties of Al–Cu–Mn Alloy

Rare earth(RE) elements have positive e ects on Al alloy, while most research is focused on microstructure and mechanical properties. As important application indices, toughness and plasticity are properties that are sensitive to alloy fracture characteristics, and few research studies have characterized the fracture properties of Al–Cu–Mn alloy on RE elements. The e ect of di erent contents of Y on the fracture properties of Al–Cu–Mn alloy is investigated. T6 heat treatment(solid solution and artificial aging treatment), optical microscope(OM), scanning electron microscopy(SEM) and energy dispersive spectrometer(EDS) methods are applied to the alloy. Results showed that when Y ele?ment is present at 0.1%, the section of the as?cast alloy has smaller sized dimples and the fracture mode presents duc?tile features. Slight changes in hardness are also observed and maintained at about 60 HV. With increasing content of the RE element Y from 0.1 to 0.5%, the θ phase and Cu atoms in the matrix were reduced and most stopped at Grain boundaries(GBs). Micro?segregation and an enriched zone of Y near the GBs gradually increased. At the same time, the inter?metallic compound AlCuY is aggregated at grain junctions causing deterioration of the micro?structure and fracture properties of the alloy. After T6 treatment, the flatness of the fracture surface was lower than that of all the as?cast alloy showing lots of dimples and teared edges with a significant increase in hardness. When Y content was 0.1%, the strength and hardness of the alloy increased due to refinement of the grain strengthening e ect. The content of Y elements segregated in the inter?dendritic zone and GBs is reduced. Plasticity and deformation compatibility also improved, making cracks di cult to form and merge with each other along adjacent grain junctions and providing an increased potential for ductile fracture. This paper proposes the addition of RE Y as an e ective and prospective strategy to improve the fracture properties of the Al–Cu–Mn alloy and provide a meaningful reference in terms of improving overall performance.

Cavitation Erosion Behavior of as-Welded Cu12Mn8Al3Fe2Ni Alloy

Cavitation erosion behavior of as-welded Cu12Mn8Al3Fe2Ni alloy in 3.5% NaCl aqueous solution was studied bymagnetostrictive vibratory device for cavitation erosion. The results show that the cavitation erosion resistance ofthe as-welded Cu12Mn8Al3Fe2Ni alloy is much more superior to that of the as-cast one. The cumulative mass lossand the mass loss rate of the as-welded Cu12Mn8Al3Fe2Ni alloy are almost 1/4 that of the as-cast one. SEM analysisof eroded specimens reveals that the as-cast Cu12Mn8Al3Fe2Ni alloy is attacked more severely than the as-weldedone. Microcracks causing cavitation damage initiate at the phase boundaries.