The Directory of Open Access Journals (DOAJ) includes free, full-text, quality-controlled scientific and scholarly journals covering a variety of subjects, including materials, mechanical engineering, optics, and more. There are currently over 3300 journals in the DOAJ, and 1100 of those journals are searchable at the article level.
Open access publications are those that do not charge individuals or institutions for access to materials. For any journal or publication to be considered for addition to the DOAJ, it must include readers' rights to not only read but to download, copy, distribute, print, search, or link to the full text of the material. 'Quality control' is considered to be through either peer review or editorial quality control.