Production of hypereutectic Al-Si alloys by P/M route

In this work hypereutectic aluminium silicon alloys with high silicon content that are difficult to produce by casting, are produced by powder metallurgy (P/M) route. Different alloys are produced with varying silicon content. Aluminium silicon alloys are produced by both hot pressing and sintering of aluminium and silicon powder mixtures for the comparison. The production of hypereutectic Al-Si alloys by sintering of powder compacts is found to be unfeasible in terms of obtaining high density. The hardness and the density values of the alloys containing same amount of silicon, are higher in the alloy produced by hot pressing than the sintered alloys. The increase in hardness of the alloys is observed by increasing the silicon content. 100% theoretical density and 422 kg mm(-2) MHV hardness values are reached for the Al-67%Si composite which is hot pressed under 500 MPa and at 600 degrees C.