Letter to the Editor Comparison of data obtained by dilatometric technique and magnetothermal method during isochronal annealing of amorphous electroless Ni–P S. Armyanov * , D. Tachev Institute of Physical Chemistry, Bulgarian Academy of Sciences, Blok 11, Academic G. Bonchev St., Sofia 1113, Bulgaria Received 16 August 2002 Abstract A juxtaposition of two methods both presenting the rates of change during crystallization of amorphous alloys and being based on different effects of the occurring transformation is presented. Magnetothermal analysis is sensitive to the precipitation of strong magnetic phase. Differential dilatometric technique is displaying the rate of length change during amorphous Ni–P crystallization. A comparison of the results obtained by these two methods with the differential scanning calorimetry data is made. Recommendations for the application of these three methods are given. Ó 2003 Elsevier B.V. All rights reserved. PACS: 65.70.+y; 75.50.Kj; 81.05.Kf; 81.15.Pq; 81.30.Mh; 81.70.Pg Electroless deposited amorphous Ni–P films have a number of applications [1] and particularly are an important component in a wide array of electronic devices. A good example is the potential of electroless deposition for low-cost under bump metallization (UBM) in flip-chip packaging [2,3]. The investigation of the crystallization of amor- phous Ni–P alloys is very significant for UBM [3], for the preparation of materials with nanocrys- talline structure [4], as well as for many other applications. Without any doubt the study of dif- ferent aspects of crystallization is also of a great academic interest and fundamental importance. In previous papers an attempt was made to use new magnetothermal analysis to display in a dif- ferent way the changes occurring during isochronal (with constant rate) annealing of amorphous Ni–P [5,6]. The essence of the method is that the mag- netization of the sample measured during the heating is divided by the magnetization determined at the same temperature but after complete crys- tallization of the amorphous alloy. Thus this ratio is the share of precipitated nickel at the relevant temperature and heating rate with respect to the total amount of the separated nickel. Besides, in this way the influence of the magnetization temperature dependence is eliminated. By differentiation of the described ratio a quantity is obtained directly * Corresponding author. Fax: +359-2 971 26 88. E-mail address: armyanov@ipchp.ipc.bas.bg (S. Armya- nov). 0022-3093/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0022-3093(03)00523-4 Journal of Non-Crystalline Solids 328 (2003) 250–253 www.elsevier.com/locate/jnoncrysol LETTER TO THE EDITOR