Disclosed are metal alloy particles containing substantially no lead, each exhibiting a plurality of different melting points including an original lowest melting point (a) and a highest melting point, wherein, when the metal alloy particles are subjected to differential scanning calorimetry (DSC), at least one exothermic peak is observed in the DSC, wherein each of the metal alloy particles exhibits the original lowest melting point (a) at least at a surface portion thereof, and wherein, when each metal alloy particle is heated at a temperature equal to or higher than the original lowest melting point (a) to melt at least a surface portion of each metal alloy particle, followed by cooling to room temperature to thereby solidify the melted portion of each metal alloy particle, the resultant solid metal alloy particle having experienced the melting and solidification exhibits an elevated lowest melting point (a') higher than the original lowest melting point (a).