Effect of Ti and Ce Microalloy on Microstructure and Properties of Al-Si-Cu-Zr-Sr Cast Aluminum Alloy

The effect of Ti and Ce microalloying on the mechanical properties of Al-9Si-3.5Cu-0.2Zr-0.1Sr cast aluminum alloy was investigated,and it was hoped that the cast aluminum alloy with excellent comprehensive properties could be obtained.On the basis of Zr-Sr microalloyed cast aluminum alloy(Al-9Si-3.5Cu-0.2Zr-0.1Sr),the effects of 0.2Zr-0.1Sr-0.16Ti ternary microalloying and 0.2Zr-0.1Sr-0.16Ti-0.1Ce quaternary microalloying on the microstructure and properties of the alloy were investigated.The experimental results show that compared with Zr-Sr microalloying,Zr-Sr-Ti microalloying and Zr-Sr-Ti-Ce microalloying can effectively refine the microstructure,improve the modification effect of Si phase,and promote the improvement of Al_(2)Cu phase,thus improving the properties.The higher the degree of microalloying,the hardness is gradually increasing,but the electrical conductivity is gradually decreasing.Zr-Sr-Ti microalloying can increase the tensile strength of the alloy to 400.07 MPa and the elongation to 9.5%.Zr-Sr-Ti-Ce microalloying do not continue to improve the properties of the alloy,and the tensile strength and elongation after fracture decrease to a certain extent due to the addition of Ce.Therefore,the best comprehensive properties can be obtained by ZrSr-Ti microalloying(Al-9Si-3.5Cu-0.2Zr-0.1Sr-0.16Ti).

Low-cycle fatigue behavior of permanent mold cast and die-cast Al-Si-Cu-Mg alloys

Fatigue failure is one of the main failure forms of Al-Si-Cu-Mg aluminum alloys. To feature their mechanical aspect of fatigue behavior, the low-cycle fatigue behavior of permanent mold cast and die-cast AI-Si- Cu-Mg alloys at room temperature was investigated. The experimental results show that both permanent mold cast and die-cast AI-Si-Cu-Mg alloys mainly exhibit cyclic strain hardening. At the same total strain amplitude, the diecast AI-Si-Cu-Mg alloy shows higher cyclic deformation resistance and longer fatigue life than does the permanent mold cast AI-Si-Cu-Mg alloy. The relationship between both elastic and plastic strain amplitudes with reversals to failure shows a monotonic linear behavior, and can be described by the Basquin and Coffin-Manson equations, respectively.

Corrosion performance of high pressure die-cast Al-6Si-3Ni and Al-6Si-3Ni-2Cu alloys in aqueous NaCl solution

The corrosion performance of high pressure die-cast Al？6Si？3Ni （SN63） and Al-6Si-3Ni-2Cu （SNC632） alloys in 3.5%（mass fraction） NaCl solution was investigated. X-ray diffraction （XRD） and microstructural studies revealed the presence of singlephase Si and binary Al3Ni/Al3Ni2 phases along the grain boundary. Besides, the single Cu phase was also identified at the grainboundaries of the SNC632 alloy. Electrochemical corrosion results revealed that, the SNC632 alloy exhibited nobler shift incorrosion potential （φcorr）, lower corrosion current density （Jcorr） and higher corrosion resistance compared to the SN63 alloy.Equivalent circuit curve fitting analysis of electrochemical impedance spectroscopy （EIS） results revealed the existence of twointerfaces between the electrolyte and substrate. The surface layer and charge transfer resistance （Rct） of the SNC632 alloy was higherthan that of the SN63 alloy. Immersion corrosion test results also confirmed the lower corrosion rate of the SNC632 alloy andsubstantiated the electrochemical corrosion results. Cu addition improved the corrosion resistance, which was mainly attributed to theabsence of secondary Cu containing intermetallic phases in the SNC632 alloy and Cu presented as single phase.