Thx Neil!This was my solution:
public class AttributeTableManager
{
private IFeatureLayer _featureLayer;
public AttributeTableManager(IFeatureLayer fl)
{
this._featureLayer = fl;
}
/// <summary>
/// Altera o alias do campo
/// </summary>
/// <param name="fieldName">Name do campo na attributetable, ele é usado para procurar o campo correto e alterar o alias</param>
/// <param name="alias">Alias que será definido para o campo</param>
public void ChangeAliasName(string fieldName,string alias)
{
ILayerFields fields = this._featureLayer as ILayerFields;
IFieldInfo fldInfo = fields.FieldInfo[fields.FindField(fieldName)];
fldInfo.Alias = alias;
}
}