Investigation On Preparation,Microstructure And Mechanics Of Al-Ni Alloy

Al-x wt.% Ni alloys(x = 0.1 and 0.2)with different Ni contents were prepared by semi-continuous casting method using 99.9 wt.% industrial pure Al and 99.999 wt.% Ni powder.After the homogenization heat treatment of the alloy at 530 °C×12 h,the effect of different solution time on the microstructure and mechanical properties of the alloy was studied at a temperature of 600 °C.The alloy was subjected to T6 single stage aging treatment and T8 strain aging treatment respectively.The performance characterization and histological observation of the samples were carried out by means of hardness test,conductivity measurement,metallographic observation(OM),scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).The morphology and microstructure of the Al-Ni alloy ingot were observed and analyzed,it was found that the Ni element could refine the grain size.Then the solution temperature of 600 °C was selected.The relationship between the hardness,conductivity and holding time of Al-0.1Ni and Al-0.2Ni alloy in the solution treatment was studied and it was found that the hardness of the two alloys up first and then going down,the conductivity increased gradually during the solution process.At the same time,the evolution rule of the microstructure and phase structure of the alloy during solid solution was observed.After 600 °C×12 h solution treatment,most of the coarse primary phase can be dissolved into the matrix.Finally,the aging and the cold rolling-aging treatment were be compared and optimized.After the Al-Ni alloy was treated at 600 °C for 12 h,the ally were be prepared by different parameters of aging treatment.The results show that the alloy can get the highest hardness when the aging temperature is 250 °C,and the variation law of the 40%,60% and 80% cold-rolled deformation T8 treatment are the same as those of T6 aging: the hardness increases and reaches the peak and then goes down.The cold rolling deformation can promote the precipitation of secondary phase such as Al3 Ni,and shorten the peaking aging time.When Ni is added to the aluminum,some Ni element is dissolved into the aluminum alloy matrix,and the excess can precipitate from the matrix in the form of intermetallic compounds.Ni element can not only form the Al3 Ni compounds with a-Al,but also can form the Al9 FeNi phase,which can eliminate the bad effects of Fe element in Al alloy.At the same time,the alloy strength significantly increased because of a large number of dislocations introduced by cold rolling.The 80% cold-rolled alloy can get the best comprehensive performance during the aging treatment,which have a conductivity of 61.8%(IACS)and a hardness of 46.34 HV,its tensile strength can reach 133.29 MPa with a suitable elongation.