2.5. Evaluation of microhardness
The microhardness of untreated Ti–15Mo alloy and those subjected to TO at different temperatures, for various periods of time,were measured using a Vickers microhardness tester (Mitutoyo hardness testing machine, Tokyo, Japan) with a Vickers diamond indenter under a load of 100 g. The lap time for each indentation was 15 s and the values reported represent the average of five measurements.