moreover since sn is inexpensive in comparison with in and provides change in alloy composition approximate to the change in composition due to addition of in it is possible to remarkably reduce manufacturing cost of the filler metal alloy composition fig6 is a graph showing a test example of a ag u2014 cu u2014 zn based filler metal alloy composition for a coolant circulating pipe in accordance with first to third embodiments of the present invention in which hardness of the composition at different si contents is measured fig7 is a graph showing a test example of a ag u2014 cu u2014 zn based filler metal alloy composition for a coolant circulating pipe in accordance with first to third embodiments of the present invention in which spreadability of the composition at different si contents is measured table 2 shows embodiments 1 to 3 of the ag u2014 cu u2014 zn based filler metal alloy composition for coolant circulating pipe brazing in accordance with the present invention in which si is added to a tertiary system of a ag u2014 cu u2014 zn alloy and the cross sectional view filler metal alloy composition comparative example 1 referring to fig6 and 7 and table 2 it will be appreciated that the filler metal alloy composition test example 9 including 20 wt ag 41 wt cu 2 wt sn and 37 wt zn as the ag u2014 cu u2014 zn based filler metal alloy composition for coolant circulating pipe brazing in accordance with the.