Whisker filaments of SiC that are 5 μm thick are coated withan aluminum alloy using a chemical bonding process. The coating process is carried out at 650 oC before the sample iscooled to room temperature. Elastic stresses due to thermal expansion mismatch do not begin to appreciably accumulate until the alloy has cooled to approximately 200 oC due to alloyviscosity. If the stresses necessary to maintain whisker/coating compatibility are assumed to be normal stresses acting only in thedirection of the filament axis, what is their sign and magnitude at20 oC? Relevant materials properties are:ESiC = 476 GPA, EAl = 70 GPA,αSiC = 4.7 x 10-6/oC,αAl = 21 x 10-6/oC.