Mechanism of reactive sintering of MgAlB14 by pulse electric current

The reactive sintering of the hard boride AlMgB14 from the elements was investigated using the pulse electric current sintering (PECS) method. The mechanism of formation of AlMgB14 was investigated over the temperature range 600-1400 degrees C. The formation of AlNgB(14) begins at as low a temperature as 800 degrees C and is essentially complete at 1325 degrees C. Thus the Prospect Of forming nanostructured AlNgB14 is not high since earlier nucleated grains continue to grow up to the maximum sintering temperature. Under optimum conditions, the products contained AlMgB14 With a similar to 93 vol%, the remaining Phases include spine] and impurity from milling. The product had a hardness of 26.1 GPa and a fracture toughness of 3.1 MPa m(1/2). (C) 2008 Elsevier Ltd. All rights reserved.