Studi pengaruh temperatur penuaan terhadap sifat mekanik dan struktur mikro paduan Al-5.1Zn-1.8Mg-0.4Ti (% berat) hasil squeeze casting = Effect of ageing temperature on mechanical properties and microstructure of Al-5.1Zn-1.8Mg-0.4Ti alloy (wt.%) fabricated by squeeze casting