Temperature Effect on Creep and Fracture Behaviors of Nano-SiO2-composite and AlSi12Cu3Ni2MgFe Aluminum Alloy

Abstract

In the presented article, the temperature effect was studied on creep properties and fracture behaviors of AlSi12Cu3Ni2MgFe aluminum-silicon alloys, unreinforced and reinforced with SiO2 nano-particles. For such objective, standard specimens were fabricated by gravity casting and stir-casting methods, for aluminum alloys and nano-composites, respectively. Then, force-controlled creep testing was performed on standard specimens at 250, 275 and 300°C, under 100 MPa. Then, to find failure mechanisms, the fracture surface of test samples was also analyzed by the field emission scanning electron microscopy. Experimental results depicted the temperature changed creep behaviors of both materials, effectively. Moreover, a significant improvement in creep properties was observed by reinforcing the aluminum matrix with nano-particles, besides a heat treatment process. Such an increase in the creep lifetime was higher at 300°C. In addition, the fracture surface investigation of both materials implied the same brittle behavior, with quasi-cleavage marks. The failure location changed from inside the intermetallic phase into boundaries of the intermetallic phase in the nano-composite.

Archives of Foundry Engineering

“…Another intermetallic phase was (Al,Ni) with a black-colored area. Similar phases have been reported in the literature [14][15][16][17][18][19]. The image of the field-emission scanning electron microscopy from corroded surfaces for aluminum-silicon alloys after 200 hours of the immersion time in the acidic environment before fatigue testing is shown in Figure 6.…”

“…Based on this figure, the dominated phase was α-Al as the matrix [12]. The silicon phase was as a major precipitate, dispersed in the aluminum matrix, and observed in two shapes, blocky and Chinese-script morphologies [12,[14][15][16]. Another precipitate consisted of an intermetallic phase that was the (Al,Cu) phase.…”

“…The sample after the pre-corrosion seemed to be darker, compared to the initial specimen. For such an objective, a polishing process was firstly performed on specimens and then, a Keller etchant (the environment including 95 ml H 2 O, 2.5 ml HNO 3 , 1.5 ml HCL and 1.0 ml HF) was utilized [13][14][15]. To study the fracture surface, the field-emission scanning electron microscopy was also used to find the failure mechanism under bending cyclic loadings.…”