engleski

Effect of thickness on properties of Cu-Ti, Zr, Hf glassy ribbons

Being unstable in respect to both crystalline and ideal glassy state the properties of metallic glasses (MG) depend sensitively on the preparation conditions (thus thickness for melt - spun ribbons). We present first measurements of the effect of thickness (i.e. quenching rate) on the properties of CuxTE100-x (TE = Ti or Hf, x ≤ 70) and Cu55 Hf45-x(Zr, Ti)x (x ≤ 45) glassy ribbons. Both, as-cast and relaxed (short anneal just below glass transition temperature, Tg) samples were studied. The mechanical properties (ultrasound velocity, Young`s modulus, microhardness) of as-cast alloys showed clear effect of thickness superposed on that due to variation in composition (x), whereas those of relaxed samples showed no effect of thickness. As expected, the mechanical properties of relaxed samples were higher than those of corresponding as-cast alloys and in ternary Cu55 Hf45-x(Zr, Ti)x alloy the effect of relaxation was larger for x = Ti than for Zr which may indicate the interplay between nearly overlapping α- and β- relaxations in Cu– base MGs [1]. Since the effect of thickness distorts the compositional variations of properties in the as-cast MGs (Fig. 1), this may lead to erroneous conclusions [2]. [1] H.- B. Yu, W.-H. Wang, K. Samwer, Mater. Today 16 (2013) 183 –191. [2] R. Ristić et al., J. Alloys Comp. 621 (2015) 136-145 and reference therein.

thickness; ribbons; properties

nije evidentirano