Solubility of boron in Mo5+ySi3-y

Using X-ray analysis, optical microscopy, chemical analysis, and electron p robe microanalysis (EPMA) it has been determined that the level of boron so lubility in Mo5+ySi3-y at 1800 degrees C reaches a maximum value of approxi mately 2 at% in a narrow region within the homogeneity range of -0.08 less than or equal to y less than or equal to 0.04. Both the B doped and undoped Mo5+ySi3-y (T1) have the tetragonal W5Si3 crystal structure, which corresp onds to the I4/mcm space group. Within the single phase Mo5+ySi3-yBx (T1) r egion then is a contraction in the lattice Volume with increasing boron con centration while there is an increase in cell volume with an increase in Mo :Si ratio. (C) 2000 Elsevier Science Ltd. All rights reserved.