Abstract: As an alternative to 3He neutron detectors, boron-coated neutron detectors have been a current focus for researchers worldwide. For the boron-coated neutron detectors, a B4C film with low stress and good adhesion to the Al substrate is required. To enhance adhesion of the B4C films on Al substrates, a B4C film with low stress was fabricated by direct current sputtering technique without substrate-heating. The Mg-Al alloy thin film was introduced between the B4C film and its substrate for enhancing the adhesion. The effect of sputtering pressure on the stress of B4C films during deposition was studied. Additionally, the adhesion of B4C films using Mg-Al films as adhesive layers and effects of sputtering pressure and alloy film thickness on adhesion were studied. Scanning and transmission electron microscopies were used to characterize the microstructure. Experimental results show that the stress of B4C films decreases and stabilizes when sputtering pressure increases during deposition. Thin and porous Mg-Al films react well with both B4C films and Al2O3 on Al substrates to enhance adhesion of the B4C films, without substrate-heating.