Effect of a whisker surface treatment on the strength of Al18B4O33 whisker reinforced AC4CH aluminum alloy composites

A new surface treatment method for aluminum borate whisker was developed in order to suppress the interfacial reaction between the whisker and aluminum alloy. By depositing Mg on the whiskers under 10 Pa at 650 degreesC for 3.6 ks, and heating them in air at 800 degreesC for 1.8 ks, a uniform MgAl2O4 layer with a thickness of 10-20 nm covered the whisker. MgAl2O4 layer had a close bonding to the whisker. P lo treatment whisker, SiO2 binder added whisker, Mg coated whisker and MgAl2O4 coated whisker reinforced AC4CH aluminum alloy composites were fabricated by squeeze casting, respectively. Compressive strength of the whisker preforms having Mg coat and MgAl2O4 coat increased remarkably. The deformation of the preform was avoided during squeeze casting. Tensile strength of Mg coat whisker reinforced composites did not decrease, and that of MgAl2O4 coat whisker reinforced composites was enhanced by 37% alter aging treatment (T6). The interface having MgAl2O4 coat showed a stable state. MgAl2O4 coat can be regarded as a good barrier to prevent the interfacial reaction between aluminum borate whisker and aluminum alloy matrix.