Wear Behaviour of Squeeze-Cast Al 2014 Alloy and <i>In-Situ</i> 5 vol% TiB₂/2014 Composite

Abstract

Dry sliding wear behaviour of gravity-cast and squeeze-cast Al 2014 alloys and in-situ 5 vol% TiB 2 /2014 composites has been studied. Squeeze casting at different pressures has been performed on the alloy and composite. Wear tests carried out at loads of 9.858.8 N on a pin-ondisc machine show that both the squeeze-cast alloy and composite are more wear resistant than their gravity-cast samples. For the squeeze-cast alloys, the sample solidified at a squeeze pressure of 60 MPa shows the least wear rate. However, in the case of the squeeze-cast composites, the wear resistance of the sample solidified at a squeeze pressure of 120 MPa is the best. The wear rates decrease with increasing hardness. A detailed SEM study of wear surface and debris is carried out to substantiate the wear results. The results indicate that the improvement in wear resistance for the squeeze-cast alloy and composite is mainly attributed to the increase in hardness and reduction in casting defects such as gas porosities and shrinkage porosities. In addition, for the squeeze-cast composite, the effect of improved dispersion of TiB 2 particles on the wear resistance is also discussed.

Effect of CeO2 on the elevated-temperature wear behaviour of in situ TiB2/A356 composite

“…The results demonstrated that the addition of La could, simultaneously, refine the second dendrite arm spacing of α-Al grains and modify the coarse needle flake eutectic Si into fine fibrous particles, and the mechanical properties of composites, especially the elongation which has been nearly doubled compared with the composite without La addition. In our previous study, the present authors [12] indicated that the improvement in the dispersion of TiB 2 particles could significantly increase the wear resistance in the squeeze-cast in situ TiB 2 /2014 Al composites. In addition, Tjong et al [22] indicated that in the process of thermal cycling, the dimensional stability of the TiB 2 /Al composite was improved compared to the Al matrix.…”

“…Michael Rajan et al [15] investigated the wear resistance of in situ TiB 2 /AA7075 composites at 30–240°C, and indicated that the in situ TiB 2 particles were effective to enhance the wear resistance of the composite at all test temperatures and the in situ formed TiB 2 particles pushed the mild to severe wear transition temperature by 30°C. However, previous studies [1,2,12,16,17] showed in the in situ TiB 2 /Al composite, a large number of agglomerations of TiB 2 particles were formed and these agglomerations segregated in the grain boundaries, which weakened the advantage of in situ TiB 2 particles as strengthening phase and wear-resisting hard phase. And conventional mechanical stir was not powerful enough to break up the TiB 2 agglomerations completely.…”

“…It was reported that the wear resistance of the Al alloy can be enhanced by the incorporation of hard ceramic particles like TiB 2 [4,5], SiC [6] and Al 2 O 3 [6,7] into the Al alloys, and indicated that the tribological properties were influenced by the type, shape, size, volume content, interfaces and spatial dispersion of ceramic particles in the Al matrix [8]. Previous researches indicated clear ceramic particle–matrix interfaces without the presence of porosity and reaction products, and homogeneous distribution of ceramic particles in the Al matrix composite can result in effective load transfer and obtain higher properties [4,9-13]. Therefore, the in situ TiB 2 reinforced Al alloy matrix composites prepared by a simple and low-cost exothermic reaction among K 2 TiF 6 , KBF 4 and Al melts were widely investigated due to the fine particles (<1 μm), clear interfaces and strong interfacial bonding.…”

Aging Behavior of <i>In-Situ</i> TiB₂ Particles Reinforced 2014Al Alloy Composites

“…The speci c process and squeeze casts have been reported in the previous paper. 20) The specimens were taken from the top of the composite and 2014Al alloy casts, respectively. The microstructures of the composite were shown in Fig.…”